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

Author: Lu Guo
Publisher:
ISBN:
Category :
Languages : en
Pages : 97

Get Book Here

Book Description
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.