Specific-heat study of the spin-structural change in pyrochlore Nd2Mo2O7 -: art. no. 060401

By measurements of specific heat, we have investigated the magnetic field (H) induced spin-structural change in Nd2Mo2O7 that shows intriguing spin-chirality-related magnetotransport phenomena. With increasing H, a broad peak around 2 K caused by the ordering of 2-in 2-out structure of the Nd moments shifts to the lower temperature (T) up to around 3 T and then to the higher T above around 3 T irrespective of the H-direction. This is due to the crossover from antiferromagnetic to ferromagnetic arrangement between the Nd and Mo moments. While the peak T increases monotonically above 3 T for Hparallel to[100], another peak emerges around 0.9 K at 12 T for Hparallel to[111], which is ascribed to the emergence of 3-in 1-out structure. For Hparallel to[110], a spikelike peak is observed at around 3 T, which is caused perhaps by some spin flip transition.