The magnetostructural and magnetocaloric properties of CoMnGe1−xGaxB0.015CoMnGe1−xGaxB0.015 (x=0.05 and 0.06) alloys

• The entropy change values of CoMnGe1−xGaxB0.015CoMnGe1−xGaxB0.015 (x= 0.05 and 0.06) alloys are −6.2 J kg−1 K−1 and −8.7 J kg−1 K−1 under ΔH=2T.
• The main contribution to entropy change comes from the structural phase transition.
• The boron doped CoMn(GeGa) alloys could open up new possibilities for searching magnetocaloric materials.

The magnetostructural and magnetocaloric properties of CoMnGe1−xGaxB0.015CoMnGe1−xGaxB0.015 (x  =0.05 and 0.06 are named Alloy-1 and Alloy-2, respectively) alloys have been investigated by X-ray powder diffraction, calorimetric and magnetization measurements. Both alloys have hexagonal structures at room temperature and show first order phase transition below room temperature. The entropy change-ΔSΔS of these alloys are calculated as −22.1 J kg−1 K−1 (for Alloy-1 alloy) and −27.1 J kg−1 K−1 (for Alloy-2 alloy) under ΔH=7T. Magnetic hysteresis losses of these alloys are very small when compared with the undoped alloy. Considering the high magnetocaloric effect and low magnetic hysteresis features, boron doping on CoMnGe family alloys provides an alternative method to tailor magnetic and magnetocaloric properties.