Low-temperature heat transport of Nd2CuO4: Roles of Nd magnons and spin-structure transitions

Abstract

We report the magnetic-field dependence of thermal conductivity ($\ensuremath{\kappa}$) of an insulating cuprate Nd${}_{2}$CuO${}_{4}$ at very low temperatures down to 0.3 K. It is found that, apart from the paramagnetic moments scattering on phonons, the Nd${}^{3+}$ magnons can act as either heat carriers or phonon scatterers, which strongly depends on the long-range antiferromagnetic transition and the field-induced transitions of spin structure. In particular, the Nd${}^{3+}$ magnons can effectively transport heat in the spin-flopped state of the Nd${}^{3+}$ sublattice. However, both the magnon transport and the magnetic scattering are quenched at very high fields. The spin reorientations under the in-plane field can be conjectured from the detailed field dependence of $\ensuremath{\kappa}$.