スピン1/2のカゴメ格子反強磁性体の基底状態と磁気励起

抄録

Ground states and magnetic excitations of spin-1/2 kagomé antiferromagnets (KAF) A₂Cu₃SnF₁₂ (A = Cs and Rb) were investigated by the magnetic measurements and neutron scattering experiments. For A = Cs, the system undergoes antiferromagnetic phase transition at T_N = 20K. On the other hand, for A = Rb, non-magnetic “pinwheel” VBS state is realized at the ground state which is assisted by the lattice distortion to form an exchange network consisted of four different magnetic interactions. The contrasting ground states between two compounds should be caused by the difference of the lattice distortion.