Thermal properties of Er(Co1−xSix)2 compounds

Results of specific heat and thermal conductivity measurements performed on the ErCo2 and Er(Co0.95Si0.05)2 compounds are presented with the emphasis on the phenomena associated with the magnetic ordering transition and their evolution with varying the chemical composition and the applied magnetic field. From specific heat data the magnetocaloric effect (MCE) in a wide temperature interval around the transition has been evaluated for several values of magnetic field. The maximum determined size of MCE makes these materials potentially applicable in magnetic cooling. The sensitivity of the Curie temperature (TC) to the Si substitution for Co without any dramatic suppression of MCE offers an effective way for tuning the temperature range available for magnetocaloric applications. The pronounced sharp thermal-conductivity anomaly in ErCo2 in the vicinity of TC is nearly suppressed in Er(Co0.95Si0.05)2. The role of spin fluctuations in these phenomena is discussed.