Magnetic entropy change plateau in a geometrically frustrated layered system: FeCrAs-like iron-pnictide structure as a magnetocaloric prototype

Monte Carlo modeling suggests that the magnetothermal features of the Fe2P-structured FeCrAs-like compound offer a promising route for the design of magnetocaloric materials. The prototype structure is modeled as antiferromagnetically coupled layered Heisenberg systems mimicking the distorted Kagome/triangular stacked architecture of FeCrAs iron-pnictide. The magnetic entropy change ΔSm(T) presents a plateau-like behavior which can be tailored by tuning either the JCr−Fe/JCr−Cr exchange energy ratio or the magnetic field. The plateau is defined by cooperative spin ordering within a ferrimagnetic region which exists between two critical temperatures separating at the lower bound () a canted antiferromagnetic phase and at the upper bound () the thermally disordered phase. The refrigerant capacity and adiabatic change of temperature are and A(H)Tp/Cm respectively, with , A(H) an increasing positive function of the field defining the height of the plateau and Cm the magnetic specific heat, whose critical behavior is related to the values.