A Unique Crystal Structure of {{Ca}}₂{{RuO}}₄ in the Current Stabilized Metallic State

The electric-current stabilized metallic state in the quasi-two-dimensional Mott insulator Ca\$_2\$RuO\$_4\$ exhibits an exceptionally strong diamagnetism. Through a comprehensive study using neutron and X-ray diffraction, we show that this non-equilibrium phase assumes a crystal structure distinct from those of equilibrium metallic phases realized in the ruthenates by chemical doping, high pressure and epitaxial strain, which in turn leads to a distinct electronic band structure. Density functional calculations based on the crystallographically refined atomic coordinates and realistic Coulomb repulsion parameters indicate a semi-metallic state with partially gapped Fermi surface. Our neutron diffraction data show that the non-equilibrium behavior is homogeneous, with antiferromagnetic long-range order completely suppressed. These results provide a new basis for theoretical work on the origin of the unusual non-equilibrium diamagnetism in Ca\$_2\$RuO\$_4\$.     «

The electric-current stabilized metallic state in the quasi-two-dimensional Mott insulator Ca\$_2\$RuO\$_4\$ exhibits an exceptionally strong diamagnetism. Through a comprehensive study using neutron and X-ray diffraction, we show that this non-equilibrium phase assumes a crystal structure distinct from those of equilibrium metallic phases realized in the ruthenates by chemical doping, high pressure and epitaxial strain, which in turn leads to a distinct electronic band structure. Density functi...     »