Cooperative Jahn-Teller transition in Li[Li_xMn_(2-x)]O_4: a muon-spin rotaion/relaxation (μSR) view

摘要

The magnetic nature of the spinel antiferro-magnet Li[Li_xMn_(2-x)]O_4 with x = 0-0.15 has been studied with muon-spin-rotation and relaxation (μ~+SR) spectros-copy. Both weak transverse field and zero field μ~+SR measurements indicate that the whole sample enters into a static disordered magnetic phase below T_N for all the samples measured; T_N = 61 K for LiMn_2O_4, whereas 27-23 K for the x = 0.05-0.15 samples. It was also clarified that both the field distribution width and the field fluctuation rate show a clear change at the Jahn-Teller transition temperature (T_(JT) = 280 K) for LiMn_2O_4, and a short-range cooperative JT distortion appears below 280 K even for Li[Li_(0.15)Mn_(1.85)]O_4 .