Composition dependence of bulk properties in the Co-intercalated transition metal dichalcogenide CoTaS

Coがインターカレートされた遷移金属ジカルコゲナイドCoTaSのバルク物性の組成依存性

Park, P.*; Cho, W.*; Kim, C.*; An, Y.*; Avdeev, M.*; 飯田 一樹*; 梶本 亮一  ; Park, J.-G.*

Park, P.*; Cho, W.*; Kim, C.*; An, Y.*; Avdeev, M.*; Iida, Kazuki*; Kajimoto, Ryoichi; Park, J.-G.*

Spontaneous Hall conductivity has recently been reported in the triangular lattice antiferromagnet CoTaS under a zero magnetic field. This phenomenon originates from the distinctive noncoplanar triple- magnetic ground state, possessing uniform real-space Berry curvature characterized by scalar spin chirality. We investigated the physical properties of CoTaS by judiciously controlling the composition, revealing a drastic change in its bulk properties, even by slight variations in cobalt composition, despite the same crystal structure. For , CoTaS keeps all the characteristics of the ground state consistent with the previous studies --- two antiferromagnetic phase transitions at and (), a large spontaneous Hall conductivity [], and a weak ferromagnetic moment along the axis. However, samples with exhibit distinct bulk properties, including the absence of both and the weak ferromagnetic moment. Our neutron diffraction data reveal that CoTaS with develops coplanar helical magnetic order with . This is entirely different from what has been seen in , explaining the observed composition dependence.