The Effect Of Magnetoelectric Coupling And Magnetic Correlations On Temperature And Field Driven Transitions In Magnetic And Multiferroic Materials

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The Effect of Magnetoelectric Coupling and Magnetic Correlations on Temperature and Field-driven Transitions in Magnetic and Multiferroic Materials

Author : Karen L. Livesey
Publisher :
ISBN 13 :
Total Pages : 119 pages
Book Rating : 4.:/5 (748 download)

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Book Synopsis The Effect of Magnetoelectric Coupling and Magnetic Correlations on Temperature and Field-driven Transitions in Magnetic and Multiferroic Materials by : Karen L. Livesey

Download or read book The Effect of Magnetoelectric Coupling and Magnetic Correlations on Temperature and Field-driven Transitions in Magnetic and Multiferroic Materials written by Karen L. Livesey and published by . This book was released on 2009 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetoelectric coupling and magnetic correlations are shown to affect coupled order parameters, magnetisation M and electric polarisation P, in a multiferroic material. A ferromagnetic ferroelectric system is considered with two types of magnetoelectric coupling (anisotropic and isotropic) which couple P to different magnetic correlations. Using a mean field calculation for anisotropic coupling, it is shown that magnetic fluctuations h(Sz i )2i alter P even for temperatures above the magnetic Curie temperature. For isotropic coupling, a Green's function technique with a Random Phase Approximation is used to calculate how transverse correlations between neighbouring magnetic spins at sites i and j, such as hSx i Sx j i, affect P. The ferroelectric transition temperature and even the order of the transition is altered by the inclusion of magnetic correlations. Thermal hysteresis of the electric polarisation is also shown to exist in this model system. The methods presented can be extended to treat multiferroic systems with more complicated magnetic orderings. Another consequence of magnetoelectric coupling is the hybridisation of magnetic/electric excitations, known as "electromagnons." We show that for a ferroelectric canted antiferromagnet (with a weak ferromagnetic moment) with isotropic magnetoelectric coupling an electromagnon mode exists. When such a material, together with a ferromagnet, form a thin film heterostructure, dipolar coupling between the films allows for the electromagnon frequency to be tuned in the microwave regime. We use an effective medium method that takes into account electromagnetic boundary conditions to find the high frequency susceptibility of such composites and identify the type of resonant modes. However, the magnetoelectric coupling is usually weak through dipolar coupling. Magnetostrictive/piezoelectric composites have been shown to have a much larger strain-mediated magnetoelectric coupling so we detail how the effective medium method can be extended to treat such systems. It has been shown that in magnetostrictive/piezoelectrive composites, electric field can drive a magnetisation reorientation transition. Such electric field control of magnetisation is one of the chief aims in the study of multiferroic materials. However, the dynamics of such an electric field-driven magnetisation reorientation have not been studied as yet, either experimentally or theoretically. As a first step, a study of how nonlinear spin wave processes (or correlations) may alter the dynamics of magnetic field-driven magnetisation reorientation in thin magnetic films is presented here. A classical Hamiltonian formalism is developed to calculate the threshold magnetisation precession angle above which threeand four-wave decay of uniform precession may occur. The analytic results for fourwave scattering are used to qualitatively explain experimental results of the magnetisation coherency during reorientation in 15 nm Ni81Fe19 films. Possible extensions to multiferroic systems are discussed briefly.

Magnetoelectric Composites

Author : Mirza I. Bichurin
Publisher : CRC Press
ISBN 13 : 0429949618
Total Pages : 280 pages
Book Rating : 4.4/5 (299 download)

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Book Synopsis Magnetoelectric Composites by : Mirza I. Bichurin

Download or read book Magnetoelectric Composites written by Mirza I. Bichurin and published by CRC Press. This book was released on 2019-02-22 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to modeling and application of magnetoelectric (ME) effects in layered and bulk composites based on magnetostrictive and piezoelectric materials. Currently, numerous theoretical and experimental studies on ME composites are available but few on the development and research of instruments based on them. So far, only investigation of ME magnetic field sensors has been cited in the existing literature. However, these studies have finally resulted in the creation of low-frequency ME magnetic field sensors with parameters substantially exceeding the characteristics of Hall sensors. The book presents the authors’ many years of experience gained in ME composites and through creation of device models based on their studies. It describes low-frequency ME devices, such as current and position sensors and energy harvesters, and microwave ME devices, such as antennas, attenuators, filters, gyrators, and phase shifters.

Strain and Charge Co-mediated Magnetoelectric Coupling in Thin Film Multiferroic Heterostructures

Author : Xinjun Wang
Publisher :
ISBN 13 :
Total Pages : 87 pages
Book Rating : 4.:/5 (936 download)

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Book Synopsis Strain and Charge Co-mediated Magnetoelectric Coupling in Thin Film Multiferroic Heterostructures by : Xinjun Wang

Download or read book Strain and Charge Co-mediated Magnetoelectric Coupling in Thin Film Multiferroic Heterostructures written by Xinjun Wang and published by . This book was released on 2015 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently, more and more researching has been focused on multiferroic materials and devices due to the demonstrated strong magnetoelectric coupling in new multiferroic materials, artificial multiferroic heterostructures and devices with unique functionalities and superior performance characteristics. This has resulted in opportunities for us to achieve compact, fast, energy efficient and voltage tunable spintronic devices. Traditionally, in magnetic materials based magnetic random access memories (MRAM) devices, magnetization is used to store the binary information. Since the high coercivity of the ferromagnetic media requires high magnetic fields for switching the magnetic states, so it needs large amount of energy. A spin torque technique that is used in Modern MRAM information writing processes minimizes the large energy for generating a magnetic field by passing through a spin-polarized current directly to the magnets. However, this two methods still consumes a lot of energy because of the large current or current density requirement to toggle the magnetic bits. Many papers reports that spin is controlled by the electrical field which supplies new opportunities for power efficient voltage control of magnetization in spintronic devices for magnetoeletric random use for memories (MERAM) with ultra-low energy consumption. However, state of the art multiferroic materials still make it chatting to realize non-volatile 180 magnetization reversal, which is desired in realizing MERAM. In a strain-mediated multiferroic system, the typical modification of the magnetism of ferromagnetic phase as a function of bipolar electric field shows a "butterfly" like behavior. This is due to the linear piezoelectricity of ferroelectric phase which has a "butterfly" like piezostrain as a function of electric field curve resulting from ferroelectric domain wall switching. Compared with charge-mediated multiferroic, the strain-mediated multiferroic system needs much higher voltage than charge-mediated, because of the thickness of ferroelectric is different. In a strain-mediated multiferroic system, the substrate is bulk materials and in a charge-mediated multiferroic system, the substrate is a thin film on dielectric material. In this work, we study the equivalence of direct and converse magnetoelectric effects. The resonant direct and converse magnetoelectric (ME) effects have been investigated experimentally. For a strain-mediated multiferroic system, we use PIN-PMN-PT, PMN-PT as the substrate. LFO, YIG, FeGaB are used as the magnetic thin film to study the tubability. This linear piezoelectric effect in converse magnetoelectric coupling would lead to "butter-fly" like magnetization vs. electric field curve which leads to a "volatile" behavior in magnetic memory system. In a charge-mediated system, we use NiFe/PLZT/Si to study the tunability. The frequency responses of direct and converse magnetoelectric effects were measured under the same electric and magnetic bias conditions. In this study, VSM and FMR are studies in different situation. Furthermore, we studied the low temperature fabricated multiferroic heterostructure, to find out the best solution to get the thin film by spin spray. Different PH and temperature are used. VSM and FMR were employed to measure properties of thin film. XRD and SEM were used to analyse the composition and surface.

Magnetically-driven Phase Transitions in Multiferroics

Author : Michael Odell Yokosuk
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

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Book Synopsis Magnetically-driven Phase Transitions in Multiferroics by : Michael Odell Yokosuk

Download or read book Magnetically-driven Phase Transitions in Multiferroics written by Michael Odell Yokosuk and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multifunctional materials provide a platform to showcase the interplay between charge, structure, and magnetism. Complex oxides, with their delicate balance of energy scales, present a unique opportunity to unravel the cross-coupling between these interactions. Moreover, spin-orbit coupling and broken symmetries give rise to new exotic physical properties in these systems. In this dissertation, I present a spectroscopic investigation of two model complex oxides under external stimuli of temperature, magnetic field, and chemical substitution. Studying these different phase transitions from a microscopic viewpoint enhances fundamental understanding of how phase transitions occur. Multiferroic magnetoelectrics are interesting materials in that the application of electric (magnetic) fields can change their magnetic (electric) state. We combine high field optical spectroscopy and first principles calculations to analyze the electronic structure of nickel tellurium oxide across the 53 K, 9 T, and 52 T magnetic transitions to reveal that the color properties are sensitive to magnetic order due to field-induced changes in the crystal field environment. We also reveal broadband nonreciprocal effects in nickel tellurium oxide in two different and underexplored symmetry orientations at much higher energies than typically observed. Infrared spectroscopy is a powerful tool to investigate a wide range of physics problems such as spin-phonon coupling, broken symmetries, the onset of metallicity, and the role of spin-orbit coupling on the lattice. When a magnetic field is applied along the easy axis of antiferromagnets, second-order spin-flop transitions are revealed via broken symmetry and large spin-orbit coupling, different than the conventional first-order mechanism. We measure the infrared vibrational properties of nickel tellurium oxide and demonstrate that the phonon anomalies are consistent with a second-order mechanism. Chemical substitution can also induce quantum phase transitions. As an example, we measure the infrared response of several different niobium-substituted europium titanium oxide systems to reveal a semiconducting to metallic state crossover. Together, these findings provide insight on how spin, charge, and the lattice couple. They also explore the fundamental mechanisms of how quantum phase transitions occur in systems with low symmetry and large spin-orbit coupling.

Journal of the Physical Society of Japan

Author :
Publisher :
ISBN 13 :
Total Pages : 936 pages
Book Rating : 4./5 ( download)

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Book Synopsis Journal of the Physical Society of Japan by :

Download or read book Journal of the Physical Society of Japan written by and published by . This book was released on 2018 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Computational Modelling of Molecular Nanomagnets

Author : Gopalan Rajaraman
Publisher : Springer Nature
ISBN 13 : 3031310381
Total Pages : 507 pages
Book Rating : 4.0/5 (313 download)

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Book Synopsis Computational Modelling of Molecular Nanomagnets by : Gopalan Rajaraman

Download or read book Computational Modelling of Molecular Nanomagnets written by Gopalan Rajaraman and published by Springer Nature. This book was released on with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Induced Magnetoelectric Coupling at a Ferroelectric-ferromagnetic Interface

Author : Jeffrey David Carvell
Publisher :
ISBN 13 :
Total Pages : 274 pages
Book Rating : 4.:/5 (862 download)

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Book Synopsis Induced Magnetoelectric Coupling at a Ferroelectric-ferromagnetic Interface by : Jeffrey David Carvell

Download or read book Induced Magnetoelectric Coupling at a Ferroelectric-ferromagnetic Interface written by Jeffrey David Carvell and published by . This book was released on 2013 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Preparation and characterization of multiferroic materials in which ferroelectricity and ferromagnetism coexist would be a milestone for functionalized materials and devices. First, electric properties of polyvinylidene (PVDF) films fabricated using the Langmuir-Schaefer method have been studied. Films of different thickness were deposited on silicon substrates and analyzed using several techniques. X-ray diffraction (XRD) data showed that PVDF films crystallize at an annealing temperature above 130 °C. Polarization versus electric field (PE) ferroelectric measurements were done for samples prepared with electrodes. PE measurements show that the coercivity of the films increases as the maximum applied electric field increases. The coercivity dependence on the frequency of the applied electric field can be fitted as . The results also show that the coercivity decreases with increasing the thickness of PVDF film due to the pinning effect. Next, we have demonstrated that those PVDF properties can be controlled by applying an external magnetic field. Samples were created in a layered heterostructure, starting with a Fe thin film, PVDF above that, and followed by another thin film of Fe. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to study the interface between PVDF polymer films and ferromagnetic iron thin films. Conventional EXAFS was applied to identify the structure of a Fe film sandwiched between two PVDF layers. An electric signal was then applied to the polymer to study the effects polarizing the polymer has on the Fe atoms at the interface. This shows that the Fe atoms diffuse into the PVDF layer at the interface between the two layers. Polarizing the film causes further diffusion of Fe atoms into the polymer. We also found that as the applied magnetic field is changed, the switching of electric polarization for the PVDF displayed a dependence on the external magnetic field. We also noticed that both the coercivity and polarization for the PVDF polymer display hysteretic features as the applied magnetic field is changed. We also found that the thickness of both the iron layers and the PVDF layer has an effect on the magnetoelectric coupling in our samples. The same strain applied to a thicker PVDF layer becomes tougher to flip the polarization compared to a thinner PVDF layer. As the iron film thickness increases, the strain also increases, and the polarization of the PVDF polymer is more easily flipped. We also found that the magnetoelectric sensitivity increases as both the PVDF and iron layers increase in thickness. We have shown that it is possible to control the ferroelectric properties of a PVDF film by tuning the magnetic field in a heterostructure. Our experiments show a coupling between the electric polarization and applied magnetic field in multiferroic heterostructures much larger than any previously reported values. Previous reports have used inorganic materials for the ferroelectric layer. Organic polymers have an electric dipole originating at the molecular level due to atoms with different electronegativity that are free to rotate. To flip the polarization, the chains must rotate and the position of the atoms must change. This increases the force felt locally by those chains. Using this polymer, we are able to increase the magnetoelectric coupling.

Effects of Chemical Substitutions and Magnetic Fields on Multiferroic and Magnetoelectric Materials

Author : Kao-Chen Liang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (868 download)

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Book Synopsis Effects of Chemical Substitutions and Magnetic Fields on Multiferroic and Magnetoelectric Materials by : Kao-Chen Liang

Download or read book Effects of Chemical Substitutions and Magnetic Fields on Multiferroic and Magnetoelectric Materials written by Kao-Chen Liang and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We studied the interaction of the magnetic order or magnetic field with polarization or dielectric properties of solids, the so-called magnetoelectric (ME) effect. In this work, we particularly consider three different classes of compounds. The first class of compound is multiferroic Mn18́2xCoxWO4. The frustrated spin helix in the multiferroic phase breaks spatial inversion symmetry and induces ferroelectric polarization. Combining neutron scattering results, we found that the strong Co anisotropy affects the orientation and shape of the spin helix, resulting in two flops of ferroelectric polarization at xc1 = 0.075 and xc2 = 0.15. At xc1 = 0.075, P rotates from the b-axis into the a 8́2 c-plane and, at xc2 = 0.15, it flips back to the b-axis. The applied external fields force the normal vector k of spin helix rotating to be parallel to the direction of the magnetic fields. This reorientation of the spin helix causes additional field-induced polarization flops. The second class of materials is ME borates. RAl3(BO3)4 (R = rare earth) crystallizes in a noncentrosymmetric but also nonpolar lattice structure, not allowing for polarization. Magnetic data show weak coupling of the f -moments in the compounds. However, RAl3(BO 3)4 shows a large ME effect and HoAl 3(BO3)4 sets the record for the highest ME effect in high fields when it was first measured. Upon strong coupling of f -moments to the lattice, the field-induced ionic displacements in a unit cell resulting in a polar distortion and a change in symmetry on the microscopic scale could be the origin of the ME effect. The third class of compound is polar LiFeP2O7. Macroscopic electric polarization originates from its polar structure. Interestingly, it also has magnetic Fe-moments to form a canted antiferromagnetic ordering at TN 9́3 27 K with a weak ferromagnetic component along the b-axis. The strong internal ME effect is proved by a sharp peak of pyroelectric current at TN, resulting in a sizable polarization decrease at the onset of the antiferromagnetic phase transition. The ME effect in external fields shows a superposition of a linear and quadratic ME effect below TN. Importantly, it proves the existence of strong coupling between magnetic order and lattice polarization, which is well-described by mean field theory.

Handbook of Solid State Chemistry, 6 Volume Set

Author : Richard Dronskowski
Publisher : John Wiley & Sons
ISBN 13 : 3527325875
Total Pages : 3912 pages
Book Rating : 4.5/5 (273 download)

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Book Synopsis Handbook of Solid State Chemistry, 6 Volume Set by : Richard Dronskowski

Download or read book Handbook of Solid State Chemistry, 6 Volume Set written by Richard Dronskowski and published by John Wiley & Sons. This book was released on 2017-10-23 with total page 3912 pages. Available in PDF, EPUB and Kindle. Book excerpt: This most comprehensive and unrivaled compendium in the field provides an up-to-date account of the chemistry of solids, nanoparticles and hybrid materials. Following a valuable introductory chapter reviewing important synthesis techniques, the handbook presents a series of contributions by about 150 international leading experts -- the "Who's Who" of solid state science. Clearly structured, in six volumes it collates the knowledge available on solid state chemistry, starting from the synthesis, and modern methods of structure determination. Understanding and measuring the physical properties of bulk solids and the theoretical basis of modern computational treatments of solids are given ample space, as are such modern trends as nanoparticles, surface properties and heterogeneous catalysis. Emphasis is placed throughout not only on the design and structure of solids but also on practical applications of these novel materials in real chemical situations.

Magnetoelectric coupling at metal surfaces

Author : Gerhard, Lukas Leander
Publisher : KIT Scientific Publishing
ISBN 13 : 3731500639
Total Pages : 144 pages
Book Rating : 4.7/5 (315 download)

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Book Synopsis Magnetoelectric coupling at metal surfaces by : Gerhard, Lukas Leander

Download or read book Magnetoelectric coupling at metal surfaces written by Gerhard, Lukas Leander and published by KIT Scientific Publishing. This book was released on 2013-12-24 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nowadays, the development of magnetic data storage devices technique faces fundamental limitations which lead to a slow-down of the increase of areal storage density. Therefore, magnetoelectric coupling which allows to change the magnetic state of matter by means of an electric field attracted significant interest. In this work, scanning tunneling microscopy was used to show for the first time that magnetic information can be written on the nanometer scale by the application of electric fields.

Magnetoelectric Coupling at Multiferroic Interfaces

Author : Michael Fechner
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (838 download)

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Book Synopsis Magnetoelectric Coupling at Multiferroic Interfaces by : Michael Fechner

Download or read book Magnetoelectric Coupling at Multiferroic Interfaces written by Michael Fechner and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When magnetism and ferroelectricity coexist in the same crystalline phase of a material it is called multiferroic. Furthermore, the crystal symmetry of a multiferroic material allows for magnetoelectric coupling which is quite useful since the coupling offers magnetization switching by an external electric field or electric polarization switching by an external magnetic field. In this thesis multiferroic interfaces are examined upon the occurrence of magnetoelectric coupling. Therefore first-principle methods based on density functional theory are used. The model system that are investigated consist of different ultrathin ferromagnetic films (Co and Fe) on top of ferroelectric ATiO3 (A=Pb, Ba) perovskites. The calculations show that at the interface a moderate change of the size of the total magnetization due to a change of the electric polarization occurs. Furthermore, the magnetic order of the Fe film is sensitive to its thickness, so an unexpected ferrimagnetic ordering appears for 2ML Fe whereas for all other thicknesses ferromagnetic ordering is preferred. Hybridization and strain effects at the interface explain the observations. Finally it is shown how the magnetic instability can be used to gain control of the magnetic ordering by the electric polarization.

Nanoscale Ferroelectrics and Multiferroics

Author : Miguel Alguero
Publisher : John Wiley & Sons
ISBN 13 : 1118935756
Total Pages : 994 pages
Book Rating : 4.1/5 (189 download)

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Book Synopsis Nanoscale Ferroelectrics and Multiferroics by : Miguel Alguero

Download or read book Nanoscale Ferroelectrics and Multiferroics written by Miguel Alguero and published by John Wiley & Sons. This book was released on 2016-05-31 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dieses Buch beleuchtet die wichtigsten Aspekte der Verarbeitung und Charakterisierung von Ferroelektrika und Multiferroika auf Nanoebene, präsentiert eine umfassende Beschreibung der jeweiligen Eigenschaften und legt dabei den Schwerpunkt auf die Unterscheidung von Größeneffekten bei extrinsischen Eigenschaften wie Rand- oder Interface-Effekte. Eingegangen wird auch auf neuartige Nanoebene. Das Fachbuch ist in drei Abschnitte unterteilt und beschreibt die Verarbeitung (Nanostrukturierung), Charakterisierung (nanostrukturierter Materialien) und Nanoeffekte. Unter Rückgriff auf die Synergien zwischen Nano-Ferroelektrika und -Multiferroika werden Materialien behandelt, die auf allen Ebenen einer Nanostrukturierung unterzogen werden, von Technologien für keramische Materialien wie ferroelektrische Nanopulver, nanostrukturierte Keramiken und Dickschichten sowie magnetoelektrische Nanokomposit-Materialien bis hin zu freistehenden Nanoobjekten mit spezifischen Geometrien wie Nanodrähte und Nanoröhren auf verschiedenen Entwicklungsstufen. Grundlage des Buches ist die europäische Wissensplattform im Wissenschaftsbereich innerhalb der Aktion von COST (Europäische Zusammenarbeit in Wissenschaft und Technik) zu ein- und mehrphasigen Ferroika und Multiferroika mit begrenzten Geometrien (SIMUFER, Ref. MP0904). Die Autoren der Kapitelbeiträge wurden sorgfältig ausgewählt, haben allesamt ganz wesentlich zur Wissensbasis für das jeweilige Thema beigetragen und gehören vor allem zu den renommiertesten Wissenschaftlern des Fachgebiets.

Multiferroicity and Magnetoelectric Effect in Novel Complex Oxides

Author : Young Jai Choi
Publisher :
ISBN 13 :
Total Pages : 150 pages
Book Rating : 4.:/5 (499 download)

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Book Synopsis Multiferroicity and Magnetoelectric Effect in Novel Complex Oxides by : Young Jai Choi

Download or read book Multiferroicity and Magnetoelectric Effect in Novel Complex Oxides written by Young Jai Choi and published by . This book was released on 2009 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiferroic materials, in which ferroelectric and magnetic ordering are simultaneously present, exhibit unprecedented physical properties due to the coupling between electric and magnetic order parameters. The significant cross-coupling effects in the newly found materials have invigorated research in multiferroics as they offer a new route toward fundamental understanding of how spin and lattice degrees of freedom interact and produce macroscopic phenomena. Furthermore, the emergence of multiple functional properties in such materials has stimulated the application in future generations of novel devices in which polarization can be controlled by a magnetic field or vice versa. Recently, the search for an enhanced coupling between dual order parameters has led to discoveries of new class of materials called magnetism-driven ferroelectrics. In such materials, ferroelectricity is induced by a fundamental new mechanism, by which magnetic orders with broken inversion symmetry result in ferroelectric distortions through exchange striction. The magnetic origin of their ferroelectricity engenders highly sensible ferroelectric properties to applied magnetic fields. Herein, we present discoveries of new multiferroics which reveal intriguing interplays between ferroelectricity and magnetism: (1) Thermal and magnetic reversal of electric polarization in the conical spiral multiferroic, CoCr2O4, (2) Collinear-magnetism-induced ferroelectricity of the Ising chain magnet Ca3CoMnO6, and (3) Multiferroicity in the square-lattice antiferromagnet of Ba2CoGe2O7. The rich physical phenomena among these new materials unveil a fascinating nature of multiferroicity.

Investigation of Magnetoelastic Coupling in Multiferroic Geometrically Frustrated Magnets

Author : Oktay Aktas
Publisher :
ISBN 13 :
Total Pages : 414 pages
Book Rating : 4.:/5 (995 download)

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Book Synopsis Investigation of Magnetoelastic Coupling in Multiferroic Geometrically Frustrated Magnets by : Oktay Aktas

Download or read book Investigation of Magnetoelastic Coupling in Multiferroic Geometrically Frustrated Magnets written by Oktay Aktas and published by . This book was released on 2012 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Engineering the Magnetoelectric Coupling in Complex Oxides Heterostructures

Author : Di Yi
Publisher :
ISBN 13 :
Total Pages : 130 pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis Engineering the Magnetoelectric Coupling in Complex Oxides Heterostructures by : Di Yi

Download or read book Engineering the Magnetoelectric Coupling in Complex Oxides Heterostructures written by Di Yi and published by . This book was released on 2015 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiferroic magnetoelectric (ME) materials, which simultaneously show ferroelectricity and magnetic ordering, have attracted a huge scientific attention due to both the intriguing fundamental importance and the great technological potential, as a result of the coupling between the dual ferroic orderings. However there are only a few single-phase multiferroic materials in nature and the performance is limited by the low ordering temperature, the small polarization/magnetization or the weak coupling efficiency. Another promising pathway to engineer ME coupling is through designing heterostructures. The current studies of ME coupling (electric field control of magnetism) in heterostructures can be divided into 3 routes: (1) Using piezoelectric effects to change the strain (lattice); (2) Using ferroelectric polarization to tune the carriers (charge); (3) Using multiferroic materials to manipulate the moments by magnetic coupling (spin). Previous studies of an all-oxide model heterostructure system that consists of the ferromagnet La0.7Sr0.3MnO3 (LSMO) and the BiFeO3 (BFO) reveals an interesting charge and spin interactions at the interface. Following the same route, the first part of the dissertation focuses on two different pathways to improve the ME coupling in manganite/BFO model system. Chapter 3 demonstrates that the ME coupling in LSMO/BFO is dramatically different by changing the atomic stack-ing sequence at the interface. In chapter 4, another model system La0.5Ca0.5MnO3 (LCMO), which is at the ferromagnetic/antiferromagnetic phase boundary, is studied instead of LSMO to explore the limit within this route. The results complementarily suggest the importance of a more comprehensive design rule at the atomic scale in order to achieve a better ME coupling efficiency. Furthermore, although the coupling between the lattice, charge and spin has been intensively studied in terms of ME coupling, the orbital degree of freedom has been neglected so far. In principle, orbital is strongly coupled to lattice. Therefore a large ME coupling could be expected if a strong spin-orbit interaction could be established. The second part of the dissertation concentrates on pursuing this new ideal through two different pathways. Chapter 5 presents a systematic study of the in-situ strain effect on the magnetic and orbital orderings of a model system Nd0.5Sr0.5MnO3. The results demonstrate the close correlation between the orbital ordering parameter and the strain. However the magnetic ordering parameter is less sensitive to strain in this system. With the implication from chapter 5, 5d transition metal oxide SrIrO3(SIO), which hosts a strong intrinsic spin-orbit coupling due to the large atomic number, is studied in chapter 6. Superlattice LSMO/SIO shows an interesting novel magnetic state with a large orbital momentum in the nominally paramagnetic SIO, which is likely to be a very promising candidate to engineer the ME coupling at the interface. In summary, our studies on engineering the ME effects in heterostructures have revealed two key implications: 1. in the traditional routes that have been extensively studied, further improvements are possible by carefully engineering the interface; 2. the coupling between spin and orbital degrees of freedom is likely to be another promising route to investigate the ME coupling in heterostructures.

The Magnetoelectric Effect in Oxide Thin Film Heterostructures

Author : Julian Irwin
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (123 download)

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Book Synopsis The Magnetoelectric Effect in Oxide Thin Film Heterostructures by : Julian Irwin

Download or read book The Magnetoelectric Effect in Oxide Thin Film Heterostructures written by Julian Irwin and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetoelectric materials are poised to make a technological impact in a world where improving efficiency and performance of electronics is increasingly important. That magnetoelectric effect is coupling of electrical and magnetic orderings provided by a single material or several coupled materials. This dissertation explores magnetoelectric effects in two different oxide thin film heterostructures. First, the intrinsic magnetoelectric effect in room temperature multiferroic bismuth ferrite (BiFeO[subscript 3]), and second the extrinsic magnetoelectric effect in strain-coupled composite membranes. Bismuth ferrite is one of the few intrinsically magnetoelectric materials with possible technological importance, as it is ferroelectric and antiferromagnetic at room temperature. Exploiting multiferroic BiFeO[subscript 3] thin films in spintronic devices requires deterministic control of both internal magnetoelectric coupling in BiFeO[subscript 3], as well as exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer. We present an approach using a monodomain magnetoelectric state with single-step switching. Here we demonstrate room temperature, deterministic and robust, exchange coupling between monodomain BiFeO[subscript 3] films and a Co overlayer that is intrinsic (i.e., not dependent on domain walls). Direct coupling between BiFeO[subscript 3] antiferromagnetic order and Co magnetization is observed, with ~ 90[degrees] in-plane Co moment rotation upon single-step switching that is reproducible for hundreds of cycles. Magnetoelectricity in piezoelectric / ferromagnetic thin-film heterostructures comes from piezoelectric strain combined with magnetostriction. In-plane magnetization rotation with an electric field across the film thickness has been challenging due to the large reduction of in-plane piezoelectric strain by substrate clamping, and in two-terminal devices, the requirement of anisotropic in-plane strain. Here we show that these limitations can be overcome two different ways in thin films. First by designing the piezoelectric strain tensor using the boundary interaction between biased and unbiased piezoelectric in (001)-oriented [Pb(Mg[subscript 1/3]Nb[subscript 2/3])O[subscript 3]][subscript 0.7]-[PbTiO[subscript 3]][subscript 0.3] (PMN-PT) membranes with ferromagnetic Ni overlayers, and second by fabricating (011)-oriented Ni/PMN-PT membranes capable of generating anisotropic strain from the symmetry of the crystal alone. We demonstrate several magnetoelectric effects including 90[degrees] rotation of in-plane magnetic anisotropy with a perpendicular electric field. Further optimization of magnetoelectric PMN-PT membrane heterostructures is expected to allow for magnetization rotation at even lower voltages and for nonvolatile magnetoelectric switching.

Oxide-Based Materials and Structures

Author : Rada Savkina
Publisher : CRC Press
ISBN 13 : 1000054314
Total Pages : 271 pages
Book Rating : 4.0/5 ( download)

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Book Synopsis Oxide-Based Materials and Structures by : Rada Savkina

Download or read book Oxide-Based Materials and Structures written by Rada Savkina and published by CRC Press. This book was released on 2020-05-07 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oxide-based materials and structures are becoming increasingly important in a wide range of practical fields including microelectronics, photonics, spintronics, power harvesting, and energy storage in addition to having environmental applications. This book provides readers with a review of the latest research and an overview of cutting-edge patents received in the field. It covers a wide range of materials, techniques, and approaches that will be of interest to both established and early-career scientists in nanoscience and nanotechnology, surface and material science, and bioscience and bioengineering in addition to graduate students in these areas. Features: Contains the latest research and developments in this exciting and emerging field Explores both the fundamentals and applications of the research Covers a wide range of materials, techniques, and approaches