By measurements of specific heat, we have investigated the magnetic field (H) induced spin-structural change in Nd2Mo2O7 that shows spin-chirality-related magneto-transport phenomena. A broad peak around 2 K caused by the ordering of 2-in 2-out structure of the Nd moments at zero H shifts to the lower temperature (T) up to around 3 T and then to the higher T above around 3 T with increasing H for all the direction of H. 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 H//[100], another peak emerges around 0.9 K at 12 T for H//[111], which is ascribed to the ordering of 3-in 1-out structure. For H//[110], a spike like peak is observed at around 3 T, which is caused perhaps by some spin flip transition.
@article{arxiv.cond-mat/0402234,
title = {Specific heat study of spin-structural change in pyrochlore Nd$_2$Mo$_2$O$_7$},
author = {Y. Onose and Y. Taguchi and T. Ito and Y. Tokura},
journal= {arXiv preprint arXiv:cond-mat/0402234},
year = {2009}
}