Observation of room temperature magnetocaloric effect in Mn0.9Ni1.1Ge alloy

We report detailed magnetic and magnetocaloric studies of a self-doped composition Mn0.9Ni1.1Ge in ambient as well as in high pressure situation. The alloy undergoes martensitic phase transition (MPT) around the room temperature and orders antiferromagnetically below 200 K. Room temperature structural analysis indicates clear signature of co-existing hexagonal and orthorhombic phases. Application of external hydrostatic pressure (P) results in a shift in the martensitic transition temperature towards the lower value. A significantly large magnetocaloric effect (MCE) around the MPT (ΔS=-6.1 J/kg-K at 295 K and −6.11 J/kg-K at 282 K during heating and cooling respectively for H changing from 0 → 50 kOe) has also been observed. The magnitude of MCE is hardly affected by the application of external P.