We report on the synthesis of perovskite SrIrO3 thin films using sputtering technique. Single phase (110) oriented SrIrO$_3$ thin films were epitaxially grown on SrTiO3 (001) substrate. Using off-axis XRD $theta-2theta$ scans, we demonstrate that these films exhibit (110) out-of-plane orientation with (001) and (1-10) lying in-plane. The sputtering grown thin films have a smooth, homogeneous surface, and excellent coherent interface with the substrate.
5d transition-metal-based oxides display emergent phenomena due to the competition between the relevant energy scales of the correlation, bandwidth, and most importantly, the strong spin-orbit coupling (SOC). Starting from the prediction of novel oxide topological insulators in bilayer ABO3 (B = 5d elements) thin-film grown along the (111) direction, 5d-based perovskites (Pv) form a new paradigm in the thin-film community. Here, we reviewed the scientific accomplishments in Pv-SrIrO3 thin films, a popular candidate for observing non-trivial topological phenomena. Although the predicted topological phenomena are unknown, the Pv-SrIrO3 thin film shows many emergent properties due to the delicate interplay between its various degrees of freedom. These observations provide new physical insight and encourage further research on the design of new 5d-based heterostructures or superlattices for the observation of the hidden topological quantum phenomena in strong spin-orbit coupled oxides.
The crystallographic orientation of SrIrO3 surfaces is decisive for the occurrence of topological surface states. We show from DFT computations that (001) and (110) free surfaces have comparable energies, and, correspondingly, we experimentally observe that single micro-crystals exhibit both facet orientations. These surfaces are found to relax over typically the length of one oxygen octahedron, defining a structural critical thickness for thin films. A reconstruction of the electronic density associated to tilts of the oxygen octahedra is observed. On the other hand, thin films have invariably been reported to grow along the (110) direction. We show that the interfacial energy associated to the oxygen octahedra distortion for epitaxy is likely at the origin of this specific feature, and propose leads to induce (001) SrIrO3 growth.
In this paper we reported, to the best of our knowledge, the first deposition of highly oriented thin films (with thickness of about 90 nm) of NdCoO3 and Nd0.8Sr0.2CoO3 cobaltites on single-crystalline STO and LAO substrates. Our investigation has shown that highly oriented single phase thin films of NCO and NSCO can be successfully deposited by means of rf-sputtering if the substrates is heated at high temperatures (700C); lower substrate temperature has shown to lead to multi-phase materials with a low crystallinity degree . LAO substrate showed to give origin to a prefect match of the out-of-plane lattice constant of the NSCO target material.
In this work, we studied phase formation, structural and magnetic properties of iron-nitride (Fe-N) thin films deposited using high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (dc-MS). The nitrogen partial pressure during deposition was systematically varied both in HiPIMS and dc-MS. Resulting Fe-N films were characterized for their microstructure, magnetic properties and nitrogen concentration. We found that HiPIMS deposited Fe-N films show a globular nanocrystalline microstructure and improved soft magnetic properties. In addition, it was found that the nitrogen reactivity impedes in HiPIMS as compared to dc-MS. Obtained results can be understood in terms of distinct plasma properties of HiPIMS.
We demonstrate the making of BaZrS3 thin films by molecular beam epitaxy (MBE). BaZrS3 forms in the orthorhombic distorted-perovskite structure with corner-sharing ZrS6 octahedra. The single-step MBE process results in films smooth on the atomic scale, with near-perfect BaZrS3 stoichiometry and an atomically-sharp interface with the LaAlO3 substrate. The films grow epitaxially via two, competing growth modes: buffered epitaxy, with a self-assembled interface layer that relieves the epitaxial strain, and direct epitaxy, with rotated-cube-on-cube growth that accommodates the large lattice constant mismatch between the oxide and the sulfide perovskites. This work sets the stage for developing chalcogenide perovskites as a family of semiconductor alloys with properties that can be tuned with strain and composition in high-quality epitaxial thin films, as has been long-established for other systems including Si-Ge, III-Vs, and II-Vs. The methods demonstrated here also represent a revival of gas-source chalcogenide MBE.