Synthesis and Properties of Epitaxial Thin Films of Pr[2]Ir[2]O[7]and Mn[3]XN (X

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ISBN 13 :
Total Pages : 97 pages
Book Rating : 4.:/5 (12 download)

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Book Synopsis Synthesis and Properties of Epitaxial Thin Films of Pr[2]Ir[2]O[7]and Mn[3]XN (X by : Lu Guo

Download or read book Synthesis and Properties of Epitaxial Thin Films of Pr[2]Ir[2]O[7]and Mn[3]XN (X written by Lu Guo and published by . This book was released on 2020 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frustrated antiferromagnetic (AFM) systems exhibit a strong correlation between the lattice, spin, and charge. Extensive studies have been performed to understand frustrated AFMs in bulk. However, studies on frustrated AFM thin films are limited due to challenges in the growth of high-quality samples. Due to a large number of energy degenerate spin states, frustrated AFM configurations are sensitive to external perturbations such as strain, structural defects or chemical disordering. Thus, epitaxial AFM thin films are the prerequisites for understanding the intrinsic magnetic properties and ground states of the spin configurations of the antiferromagnetic systems. In this work, pyrochlore Pr2Ir2O7 and Mn-based antiperovskite epitaxial thin films are chosen for study as prototypical 3D and 2D frustrated AFM systems. To address the synthetic challenges of epitaxial Pr2Ir2O7 thin films, we combine thermodynamic analysis of the Pr-Ir-O2 system with experimental results from the conventional physical vapor deposition (PVD) technique of co-sputtering. Thermodynamic calculations indicate that high deposition temperatures and high partial pressures of gas species O2(g) and IrO3(g) are required to stabilize Pr2Ir2O7. Furthermore, we find that the gas species partial pressure requirements are beyond those achievable by any conventional PVD technique. Instead, we were able to synthesize weberite-like structure pure-phase Pr3IrO7 thin films on the (111) YSZ substrates by magnetron sputtering in situ. Thus, we suggest high-pressure techniques, in particular chemical vapor deposition (CVD), as a route to the synthesis of Pr2Ir2O7, as they can support thin film deposition under the high pressure needed for in situ stabilization of pyrochlore Pr2Ir2O7. As an alternative approach, we have successfully grown epitaxial pyrochlore Pr2Ir2O7 thin films on (111) oriented yttrium stabilized zirconia (YSZ) single crystal substrates via solid phase epitaxy (SPE). While bulk Pr2Ir2O7 shows a spontaneous hysteretic Hall effect below 1.5 K, we observed the effect at elevated temperatures up to 15 K in epitaxial thin films. We conclude that the elevated-temperature spontaneous Hall effect is caused by a topological effect originating either from the Ir or Pr sublattice, with interaction strength enhanced by the Ir local moments. We have also grown high quality epitaxial thin films of the 2D frustrated AFM system Mn3XN (X=Ga and Ni) in situ by reactive magnetron sputtering with high pressure RHHED. We have characterized the thin films by x-ray diffraction measurements, Hall measurements, and magnetization measurements to investigate the strong lattice-spin-electron correlation. The high-quality Pr2Ir2O7 and Mn3XN (X=Ga and Ni) epitaxial thin films and heterostructures will provide a fertile platform for strain engineering, heterostructure design, and artificial structure design for probing and manipulating AFM spin configurations and developing spintronic device applications.

Synthesis and Properties of Epitaxial Electronic Oxide Thin-film Materials

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Total Pages : 109 pages
Book Rating : 4.:/5 (176 download)

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Book Synopsis Synthesis and Properties of Epitaxial Electronic Oxide Thin-film Materials by : David P. Norton

Download or read book Synthesis and Properties of Epitaxial Electronic Oxide Thin-film Materials written by David P. Norton and published by . This book was released on 2004 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Preparation and Properties of Epitaxial Thin Films of La1-Xbaxmn03 on Various Substrated

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Publisher : Open Dissertation Press
ISBN 13 : 9781361192412
Total Pages : pages
Book Rating : 4.1/5 (924 download)

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Book Synopsis Preparation and Properties of Epitaxial Thin Films of La1-Xbaxmn03 on Various Substrated by : Ngai-Shek Soong

Download or read book Preparation and Properties of Epitaxial Thin Films of La1-Xbaxmn03 on Various Substrated written by Ngai-Shek Soong and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Preparation and Properties of Epitaxial Thin Films of La1-xBaxMn03 on Various Substrated" by Ngai-shek, Soong, 宋毅碩, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled PREPARATION AND PROPERTIES OF EPITAXIAL THIN FILMS OF La Ba MnO ON VARIOUS SUBSTRATES 1-x x 3 submitted by Ngai-Shek SOONG for the degree of Master of Philosophy at The University of Hong Kong in December 2002 Epitaxial thin films of La Ba MnO (LBMO) were on deposited SrTiO 0.8 0.2 3 3 (100) (STO), LaAlO (100) (LAO), MgO (100) and Y O - ZrO (100) (YSZ) 3 2 3 2 substrates by using an off-axis magnetron sputtering. The properties of fabricated LBMO thin films were studied by using X-ray diffraction, dc four-probe measurements, surface profiler and atomic force microscopy. For LBMO thin films grown on STO, X-ray diffraction patterns showed that the films were highly c-axis oriented and fully epitaxial. The obtained values of full width at half maximum (FWHM) of the (002) rocking curves were small, indicating good crystallinity of the films. The temperature of insulator-metal transition, T, decreased as the thickness of the thin film increased. This was different from other systems with similar perovskite structure such as La Ca MnO and La Sr MnO . The electrical 1-x x 3 1-x x 3 resistivity of LBMO/STO thin film for temperature T2 4.5 expression of ρ(T) =ρ +ρ T +ρ T (Eq.1). The values of ρ ρ ρ all increased 0 2 4.5 0, 2, 4.5 with increasing thickness d, except d=350A, implying a phase transition may have occured. The anomalous electrical behavior of LBMO/STO system could not be explained by considering only the decreasing of transfer integral on in-plane e electrons. The orbital degree of freedom played a crucial role in determining the electrical properties of tensile-stressed LBMO thin films due to the relatively large ratio of c/a. For LBMO/LAO thin films, X-ray diffraction patterns and small FWHM values implied good crystallinity of the thin films. The decreasing value of out-of- plane lattice parameters with increasing thickness suggested the existence of compressive strain within the LBMO/LAO system. The temperature dependence of resistivity measurement showed that T decreases as the thickness of thin film increased. This is consistent with the double-exchange theory, which states that compressive strain enhances T . The temperature dependence of resistivity of LBMO/LAO thin films were also fitted well to expression (Eq.1), The values of ρ 0, ρ ρ all increased with increased thickness. 2, 4.5 La Ba MnO was also deposited on YSZ or MgO substrates respectively, 0.8 0.2 3 which having larger lattice mismatch. Peaks other than (00l) orientation were observed in X-ray measurements indicating the thin films were c-axis oriented but not highly epitaxial. A fairly large value of the FWHM of the (002) diffraction peak suggested that the films were highly crystalline. Insulator-metal (I-M) transition were not observed in LBMO/MgO films and only appear in LBMO/YSZ films with d>1200A. These were mainly due to that large lattice mismatches between LBMO and YSZ or MgO substrates which generate a large number of grains and grain boundaries in the thin films, which in turn decrease the electron transfer integral. DOI: 10.5353/th_b2663683 Subjects: Thin films Epitaxy