The physical properties of a semi-hard magnetic Fe3Pd alloy with negative enthalpy of formation

Abstract

• A ferromagnetic Fe 3 Pd ordered structure with negative enthalpy of formation is report for the first time. • The structure is mechanically and dynamically stable in the ferromagnetic state. • It is a semi-hard magnetic material suitable for magnetically coupled devices. • Electronic structure, elastic properties and thermal expansion have been determined. This study presents a theoretical calculation on the physical properties of the tetragonal Z1-type ordered Fe 3 Pd structure, and a comparison with other reported structures is performed. The Z1-Fe 3 Pd is thermodynamically, mechanically, and dynamically stable in the ferromagnetic state. Note that this tetragonal structure is the first Fe 3 Pd structure found to have a negative enthalpy of formation. Compared with the P 4/ mbm -Fe 3 Pd, the Z1-Fe 3 Pd has larger elastic modulus and higher uniaxial magnetocrystalline anisotropy constant. From the Pugh’s ratio, however, the P 4/ mbm -Fe 3 Pd is more ductile than the Z1-Fe 3 Pd. The magnetic hardness parameter shows that both Z1 and P 4/ mbm structures are semihard magnetic materials suitable for magnetically coupled devices. Unlike other Fe 3 Pd structures reported previously, for the Z1 structure the magnetic moment of the two types of Fe atoms are quite different. The Fe magnetic moment discrepancy in the Z1 structure and the thermal expansion discrepancy between the Z1 structure and other structures are analyzed with the electronic structure and the linear coefficient of thermal expansion, respectively.