Synthesis and Fundamental Investigation of Novel Correlated Electron Systems with Strong Spin-orbit Coupling

Abstract

Materials that combine both strong electronic correlation and spin-orbit coupling offer opportunities for the discovery of new states of matter. Our aim in this project is to study complex 5d transition-metal oxides with an eye towards observing unusual phenomena such as topological Mott insulators, insulator to metal transitions, the so-called spin-liquid states, and unconventional high temperature superconductivity. We propose: (i) to synthesize single crystals of Ruddlesden-Popper series of iridates (Sr2IrO4 and Sr3Ir2O7) and doped Iridate Sr2Ir1-xTMxO4 (TM: Fe, Mn, Co, Ru) and Sr2-xAxIrO4 (A: La, K), (ii) to investigate the spin-orbital excitations and coupling of phonons with electronic (orbital ordering) and magnetic phase transitions, (iii) to investigate the role of electronic correlation in the formation of charge gap and the effect of doping on the electronic structure; and (iv) to search for new possible correlated electronic states. A variety of experimental techniques already mastered by our group will be used, including Raman scattering, x-ray absorption spectroscopy, and resonant magnetic x-ray diffraction.