NMR Study of the Nonmagnetic Impurity Effect on Spin Frustration in CsCoCl₃

Abstract

A¹³³ Cs NMR experiment is performed to study the nonmagnetic impurity effect on spin frustration in the hexagonal compound CsCoCl₃, which shows successive magnetic phase transitions at T_N1=21 K and T_N2=9 K. In the low-temperature phase below T_N2, an inhomogeneous ferrimagnetic state is realized in an impure crystal containing 1.0 at% Mg ions, in which the local spin structure has the same ferrimagnetic configuration as it does in the pure case. The NMR signal disappears completely in the intermediate region between T_N2 and T_N1, suggesting a strong impurity effect on the spin dynamics.