THERMAL-CONDUCTIVITY OF RAIO(3) (R = DY, ER AND HO) IN LIQUID-HELIUM TEMPERATURES

The thermal conductivities of rare earth ortho-aluminate, DyAlO3, ErAl O3 and HoAlO3, single crystals were measured between 2 and 20 K at mag netic fields between 0 and 5 T. In zero magnetic field, the thermal co nductivities show a typical dielectric behaviour and there are large d ifferences in the peak values of the thermal conductivities. This sugg ests that the resonant phonon scattering by rare earth ions already ex ists at zero magnetic field in those perovskites. Two types of magneti c field dependencies are observed. The thermal conductivities of DyAlO 3 and ErAlO3 decrease with increasing magnetic field; however, HoAlO3 gives the opposite result. These dependencies can be qualitatively exp lained by using an energy level scheme on the ground state in Kramer o r non-Kramer ions. (C) 1998 Chapman & Hall.