DFT calculation of intrinsic properties of magnetically hard phase L1$\mathrm{_0}$ FePt

TL;DR

This study employs advanced full-potential DFT methods to precisely analyze the magnetic properties of L1₀ FePt, focusing on magnetocrystalline anisotropy and its dependence on magnetic moments, providing insights into previous discrepancies.

Contribution

It introduces detailed calculations of magnetic properties using full-potential methods and investigates MAE dependence on magnetic moments with various exchange-correlation potentials.

Findings

MAE(m) curves are nearly identical near equilibrium

Maximum MAE of about 20.3 MJ/m³ at 10% reduced magnetic moment

Results clarify discrepancies in previous MAE calculations

Abstract

Due to its strong magnetocrystalline anisotropy, FePt L1$\mathrm{_0}$ phase is considered as a promising magnetic recording media material. Although the magnetic properties of this phase have already been analyzed many times using density functional theory (DFT), we decided to study it again, emphasizing on full potential methods, including spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) and full-potential local-orbital (FPLO) scheme. In addition to the determination of exact values of the magnetocrystalline anisotropy constants K$\mathrm{_1}$ and K$\mathrm{_2}$, the magnetic moments (m), the Curie temperature, and the magnetostriction coefficient, we focused on the investigation of the magnetocrystalline anisotropy energy (MAE) dependence on the magnetic moment values using the fully relativistic fixed spin moment (FSM) method with various exchange-correlation potentials. We present nearly identical MAE(m) curves near the equilibrium point, along with different equilibrium values of MAE and magnetic moments. For a magnetic moment reduced by about 10%, we determined a theoretical MAE maximum in the ground state (0 K) equal to about 20.3 MJ m$\mathrm{^{-3}}$ and independent of the choice of the exchange-correlation potential form. These calculations allow us to understand the discrepancies between the previous MAE results for different exchange-correlation potentials.