Current-Controlled Nonequilibrium State via Current-tuned Lattice in Calcium Ruthenate

Simultaneous control of structural and physical properties via applied electrical current poses a key, new research topic and technological significance. Studying the spin-orbit-coupled antiferromagnet Ca₂RuO₄, and its derivatives with Mn-, Fe-, Rh- and Ir-doping, we find that a small applied electrical current couples to the lattice by significantly reducing its orthorhombicity and octahedral rotations, which in turn concurrently diminishes the 125 K- antiferromagnetic transition and induces a new, orbital order below 80 K. That the current-dependence of transport and magnetic properties closely tracks that of the lattice indicates that the current-controlled lattice is the driving force of the observed novel phenomena. The coupling between the lattice and nonequilibrium driven current is interpreted in terms of t_2g orbital occupancies [1].

[1] Nonequilibrium Orbital Transitions via Applied Electrical Current in Calcium Ruthenates, Hengdi Zhao et al, Phys. Rev. B 100, 241104(R) (2019)