Magnetism at high pressures: search for quantum spin liquids in 5d oxides

The connection between quantum spin liquids and possible routes to high Tc superconductivity and topological quantum computing has led to a flurry of activity aimed at generating and detecting these unusual quantum states. Realizing this elusive state of matter in real materials has been challenging as it requires fine tuning of exchange (magnetic) interactions to drive a frustrated, dynamically disordered, magnetic state. Unlike chemical doping, applied pressure has the ability to tune interatomic distances and bond angles without adding chemical disorder hence providing a unique pathway to balancing exchange interactions and stabilizing quantum spin liquid states. Third-row transition metal (5d) oxides with honeycomb- and square-lattice structures have recently emerged as potential candidates to host quantum spin liquid states as a result of strong spin-orbit coupling and large spatial extent of 5d orbitals. We search for possible emergence of spin liquid ground states in Li2IrO3 and Sr2IrO4 under the application of external pressure using newly developed capabilities for polarization-dependent x-ray resonant magnetic scattering and x-ray magnetic circular dichroism measurements.

Work at Argonne is supported by the US Department of Energy, Office of Science,
Office of Basic Energy Sciences, under Contract No. DE-AC-02-06CH11357.