Spin and orbital states in triclinic ilmenite-type CuVO

Yamamoto, Hajime*; Ochi, Keigo*; Aoyama, Takuya*; Ishii, Kenji*; Matsumura, Daiju   ; Tsuji, Takuya  ; Ogushi, Kenya*; Abukawa, Tadashi*

Ilmenite-type CuVO is a promising compound for exploring novel spin and orbital states, as Cu(3d) and V (3d) ions each form a honeycomb lattice. In this study, we synthesized triclinic ilmenite-type CuVO using a high-pressure and high-temperature method and investigated its spin and orbital states through synchrotron X-ray diffraction and measurements of electrical resistivity, magnetic susceptibility, and specific heat. The Cu ions exhibit the Jahn-Teller effect, leading to the triclinic distortion. This Jahn-Teller distortion hinders the formation of static V-V dimers, in contrast to other ilmenite-type vanadium oxides in which V-V dimerization is observed. These findings highlight triclinic ilmenite-type CuVO as a fascinating system in which each cation exhibits characteristic spin and orbital states.