Magnetic phase transitions and thermal properties of Ho(Co1-xSix)2 compounds

The specific heat of HoCo2 and Ho(Co0.95Si0.05)(2) was measured as a function of temperature in several constant magnetic fields up to 8 T. A data analysis allowed us to determine the isothermal entropy change and the magnetocaloric effect in a wide temperature range. The considerable values of the magnetocaloric effect in the vicinity of the magnetic ordering transition are qualifying both compounds as suitable for magnetic refrigeration purposes. The magnetic phase transition temperature (T-C) increases from 77 K for HoCo2 to 103 K for Ho(Co0.95Si0.05)(2) while the large magnetocaloric effect in the vicinity of TC is maintained, which demonstrates possible ways of tuning the operating temperatures of the magnetic refrigerant.