Quantum magnetisms in uniform triangular lattices LiMoO ( = In, Sc)

Iida, Kazuki*; Yoshida, Hiroyuki*; Okabe, Hirotaka*; Katayama, Naoyuki*; Ishii, Yuto*; Koda, Akihiro*; Inamura, Yasuhiro  ; Murai, Naoki  ; Ishikado, Motoyuki*; Kadono, Ryosuke*; Kajimoto, Ryoichi  

Molecular based spin-1/2 triangular lattice systems have attracted research interest. LiMoO ( = In or Sc) is such a compound where spin-1/2 MoO clusters in place of Mo ions form the uniform triangular lattice. Here, we report exotic magnetisms in LiInMoO and LiScMoO investigated by muon spin rotation (SR) and inelastic neutron scattering (INS) spectroscopies. LiInMoO exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120 spin structure. In contrast, LiScMoO undergoes short-range magnetic order below 4 K with quantum-spin-liquid-like magnetic fluctuations down to the base temperature. Origin of the different ground states is discussed in terms of anisotropies of crystal structures and magnetic interactions.