Research Projects

Although, the importance of the electron-electron correlation has been realised much earlier in 3d transition metal oxides, the manifestation of spin-orbit coupling (SOC) on the strongly correlated systems is being realised only recently. Unlike 3d elements, 4d elements has extended d orbitals, strong SOC, and significant electronic correlations U. This leads to a diverse emergent quantum phases such as quantum spin liquids, spin-orbit assisted Mott insulators, excitonic magnetism and correlated topological semimetals. The perovskite oxides of ABO3 type (A=Sr, Ca; B=Nb, Mo, Ru) with I4/mcm symmetry are theoretically predicted to host correlated topological semimetallic states. In recent days, 4d/5d oxides metals or semimetals show unsaturated linear high magnetoresistance (MR) and high mobility. For example, SrNbO3 (4d1 configuration) /SrTiO3(001) heterostructure has been reported to have high charge carrier mobility (100,000cm2/Vs) and large MR (150,000%) only in the compressively strained film. Similar behavior is also seen in the 5d based oxides such as SrTaO3 (5d1)/SrTiO3(001) heterostructure, bulk CaIrO3 (5d5). There is no universal mechanism to understand such behavior. This is often explained by electron-hole compensation, topological fermions, and inhomongeneties or scattering in the materials. This project investigates the electronic and transport properties of transition metal oxides (TMO) containing 4d/5d transition metals such as niobates and tantalates to understand the role of nontrivial band topology, inhomongeneties or defects on unusual transport behavior. We will explore the capabilities of thin film fabrication of pulsed laser deposition technique to tune the strain, dimensionality, and charge carrier doping, combined with powerful experimental techniques (X-ray photoemission spectroscopy, Physical property measurement system) to control and understand the emergent quantum phases. Nb and Ta are prone to get over-oxidized on the surface, which hinders to study the intrinsic electronic property of these materials. Therefore, we plan to use a suitable capping layer to reveal the intrinsic electronic property. Film thickness will be varied to understand the possible metal-insulator transition. Furthermore, we will explore the effect of stoichiometry, strain, defects and role of substrate etc., on the electronic and transport properties. Therefore, the substrate temperature, laser fluence and oxygen pressure will be optimized to tune/understand the high MR and high mobility behavior in these systems. Thus, a careful and systematic investigation will allow us to understand this transport properties and to control these properties for technological applications such as spintronic, high-speed electronics, memory device and magnetic sensor.