Specific heat and thermal conductivity of HoN and ErN at cryogenic temperatures

The rare earth nitrides, HoN and ErN, were synthesized by the hot isostatic pressing method. Their specific heat C-H(T) and the thermal conductivity kappa were measured at cryogenic temperatures. In zero field, the peak values of the C-0(T) of HoN and ErN are larger than those of the magnetic regenerators such as Er3Ni. The peak values of the adiabatic temperature change Delta T(T) of HoN and ErN showed similar or larger values compared with those of the candidate materials for the magnetic refrigerants such as ErAl2. The thermal conductivity of HoN and ErN are comparable to those of the magnetic regenerators such as Er3Ni. The present results indicate that HoN and ErN are promising materials as the magnetic refrigerant and regenerator for the cryogenic refrigeration system. (C) 2006 American Institute of Physics.