Low-field induced large magnetocaloric effect in Tm₂Ni_0.93Si_2.93: influence of short-range magnetic correlation

In this work, we report the successful synthesis of a new intermetallic compound Tm₂ ${Ni}_{0.93}$ ${Si}_{2.93}$ that forms in single phase only in defect crystal structure. The compound does not show any long range magnetic ordering down to 2 K. The material exhibits a large magnetic entropy change ($-\Delta S_M\sim 13.7$ J ${kg}^{-1}$ K^–1) and adiabatic temperature change ($\Delta T_{ad}\sim 4.4$ K) at 2.2 K for a field change of 20 kOe which can be realized by permanent magnets, thus being very beneficial for application purpose. In the absence of long-range magnetic ordering down to 2 K, the metastable nature of low-temperature spin dynamics and short-range magnetic correlations are considered to be responsible for such a large magnetocaloric effect over a wide temperature region. (paper)