Paramagnetic ground state with field-induced partial order in Nd_3Ga_5SiO_{14} probed by low-temperature heat transport

Abstract

We study the low-temperature heat transport of Nd_3Ga_5SiO_{14}, which is a spin-liquid candidate, to probe the nature of ground state and the effect of magnetic field on the magnetic properties. The thermal conductivity (\kappa) shows a purely phononic transport in zero field. The external magnetic field along the c axis induces a dip-like behavior of \kappa(H), which can be attributed to a simple paramagnetic scattering on phonons. However, the magnetic field along the ab plane induces another step-like decrease of \kappa. This kind of \kappa(H) behavior is discussed to be related to a field-induced partial order, which yields low-energy magnetic excitations that significantly scatter phonons. These results point to a paramagnetic ground state that partial magnetic order can be induced by magnetic field along the ab plane, which is also signified by the low-T specific heat data.