Structural, elastic, phonon and electronic properties of a MnPd alloy

Abstract

The structural, elastic, phonon and electronic properties of a MnPd alloy have been investigated using the firstprinciples calculation. The calculated lattice constants and electronic structure agree well with the experimental results. The microscopic mechanism of the diffusionless martensitic transition from the paramagnetic B2 (PM-B2) phase to the antiferromagnetic L1 0 (AFM-L1 0) phase through the intermediate paramagnetic L1 0 (PM-L1 0) phase has been explored theoretically. The obtained negative shear modulus C ′ = (C 11 − C 12)/2 of the PM-B2 phase is closely related to the instability of the cubic B2 phase with respect to the tetragonal distortions. The calculated phonon dispersions for the PM-L1 0 and AFM-L1 0 phases indicate that they are dynamically stable. However, the AFM-L1 0 phase is energetically most favorable according to the calculated total energy order, so the PM-L1 0 →AFM-L1 0 transition is caused by the magnetism rather than the electron-phonon interaction. Additionally, the AFM-L1 0 state is stabilized through the formation of a pseudo gap located at the Fermi level. The calculated results show that the CuAu-I type structure in the collinear antiferromagnetic state is dynamically and mechanically stable, thus is the low temperature phase.

Annealing time, temperature, and field dependence of pinned magnetic moments in the collinear antiferromagnet PdMn

“…11(a)) agrees with the calculation in Ref. [17]. For both ideal and defective structures, the peak at ≈ −2.5 eV is formed by strong Pd-Mn hybridization with equal contributions from Mn and Pd atoms.…”

“…The calculated lattice parameters of a = 2.82 Å and c = 3.69 Å agree with the experimental values in this work and Refs. [15,17] and with ab initio calculations [23]. The obtained lattice constants are nearly the same for both ideal L1 0 -PdMn and for the structure with Pd-excess.…”

“…The L1 0 phase of PdMn is a collinear an- * Nicolas.Josten@uni-due.de tiferromagnet, and its Néel temperature lies around 820 K [13][14][15]. At the equiatomic composition, only the Mn atoms carry a magnetic moment, which is around 4 µ B found in the results of both experimental [13,14] and ab initio theoretical studies [16,17]. The magnetic easy-axis lies within the c-plane [14], and the calculated magnetocrystalline anisotropy constant is K 2 =−1.53 × 10 6 J m −3 [18].…”

First-principles study of structural, elastic, and thermodynamic properties of ZrHf alloy

“…where E(V ) is the ground-state total energy at a given unit cell volume V , F vib (T,V ) is the vibrational energy of the lattice ions, and F el (T,V ) is the thermal electronic contribution to the free energy, which can be expressed by electronic entropy S ele (T,V ) and energy due to the electron excitations E ele (T,V ). Under quasi-harmonic approximation (QHA), [17][18][19][20][21] the F vib (T,V ) can be calculated by…”

The influence of 3d-metal alloy additions on the elastic and thermodynamic properties of CuPd3

“…[7] The addition of Mn to Pd crystal induces a diffusionless martensitic transition and shows significant changes in elastic and phonon properties. [8] Previous studies also revealed that Fe-Pd exhibited a competition between the BCC (Pd-poor and low-temperature) structure and the FCC (Pd-rich and/or high-temperature) structure. [9] Further, the Cu-Pd alloy with Pd concentration greater than 50 at% has a disordered FCC structure, while with Pd less than 18 at% it has an L1 2 -type structure and with 36 at%-46 at% Pd it has an L1 0 -type structure.…”