Great magnetic entropy change in La(Fe, M ) 13 ( M =Si, Al) with Co doping

Very large magnetic entropy change ?SM, which originates from a fully reversible second-order transition at Curie temperature TC, has been discovered in compounds La(Fe, Si)13, La(Fe, Al)13 and those with Co doping. The maximum change ?SM ? 19 J?kg-1?K-1, achieved in LaFe11.4Si1.6 at 209K upon a 5T magnetic field change, exceeds that of Gd by more than a factor of 2. The TC of the Co-doped compounds shifts to higher temperatures. ?SM still has a considerable large magnitude near room temperature. The phenomena of very large ?SM, convenience of adjustment of TC, and also the superiority of low cost, strongly suggest that the compounds La(Fe, M)13 (M=Si, Al) with Co doping are suitable candidates for magnetic refrigerants at high temperatures.