A first-principles study on the magnetocaloric compound MnFeP2∕3Si1∕3

The electronic structure and magnetic properties for MnFeP2∕3Si1∕3 with a hexagonal Fe2P-type structure have been studied by a first-principle density functional theory calculation. The calculated magnetic moments for Fe and Mn are 1.35 and 2.89μB, respectively, leading to a total magnetization of 4.15μB per formula unit due to the small negative moments of P and Si atoms. The total energy calculations show that the Si atoms prefer to occupy the 2c site rather than the 1b site and increase the moment of Fe while decreasing the moment of Mn. The nearest Mn–Fe exchange coupling interaction (JMn–Fe=1.33mRy) is much stronger than for Fe–Fe (JFe–Fe=−0.16mRy) and Mn–Mn atomic pair (JFe–Fe=−0.53mRy) interactions. The competed exchange interactions are responsible for the field induced first order magnetic transition and the large magnetocaloric effect.