Magnetism and large magnetocaloric effect in HoFe2−xAlx

Highlights: ► Structural, magnetic and magnetocaloric properties of HoFe2−xAlx compounds are reported. ► Electronic structure calculations show a good agreement between theory and experiment. ► Magnetic transitions close to room temperature for the Fe-rich samples. ► High values of the relative cooling power for all of the investigated samples. ► No hysteresis losses in applied fields of up to 4 T. - Abstract: The structural, magnetic and magnetocaloric properties of several HoFe2−xAlx compounds were investigated. The compounds in the Fe-rich region (0.36 ⩽ x ⩽ 0.4) crystallize in the cubic MgCu2 (C15) structure, while for the ones in the intermediate region (0.75 ⩽ x ⩽ 1.125) the hexagonal MgZn2 (C14) structure was observed. Electronic structure calculations were performed, showing a good agreement between theory and experiment. The Curie temperatures were found to decrease with Al content. For the Fe-rich compounds, these are close to room temperature, while for the compounds in the intermediate region, transition temperatures are well below 300 K. No magnetic hysteresis was found around the Curie temperature for applied magnetic fields of up to 4 T. All of the investigated compounds undergo a second-order magnetic phase transition at the Curie temperature. A maximum magnetic entropy change value of 7.6 J/kg K was obtained for the sample with x = 1.125, all of the samples displaying rather large RCP values. The possibility of incorporating these materials in magnetic refrigeration devices is discussed.