Theory of giant magnetocaloric effect in the shape memory alloy undergoing magnetostuctural phase transition

The theory of the giant conventional and inverse magnetocaloric effects (MCEs) is advanced on the basis of the theory of magnetism developed by A.I. Akhiezer, V.G. Bar'yakhtar, and S.V. Peletminsky in the classic monograph "Spin Waves". The MCE in the shape memory alloy undergoing the first-order phase transition from the cubic ferromagnetic (FM) phase to the tetragonal antiferromagnetic (AFM) phase is considered. The agreement between the theoretical results and existing experimental data is demonstrated. It is argued that the alloys undergoing the phase transition to AFM phases with weak exchange interaction between the magnetic sublattices are promising for use in the magnetic refrigeration technique. The possibility of observation of the giant MCE in the layered magnetic structure with weak spin-exchange coupling between the FM layers is discussed. (author)