Predicting the Curie temperature in substitutionally disordered alloys using a first-principles based model

TL;DR

This paper presents a first-principles based model to predict Curie temperatures in substitutionally disordered alloys, demonstrating broad applicability and guiding experimental efforts.

Contribution

The work introduces a robust, computationally efficient method for predicting Curie temperatures across diverse alloy systems using density functional theory.

Findings

Successfully predicts $T_C$ for multiple known alloy systems.

Demonstrates the method's applicability to unexplored Fe$_{1-x}$Tc$_x$ alloys.

Requires fewer adjustments than other theoretical approaches.

Abstract

When exploring new magnetic materials, the effect of alloying plays a crucial role for numerous properties. By altering the alloy composition, it is possible to tailor, e.g., the Curie temperature ($T_\text{C}$). In this work, $T_\text{C}$ of various alloys is investigated using a previously developed technique [Br\"{a}nnvall et al. Phys. Rev. Mat. (2024)] designed for robust predictions of $T_\text{C}$ across diverse chemistries and structures. The technique is based on density functional theory calculations and utilizes the energy difference between the magnetic ground state and the magnetically disordered paramagnetic state. It also accounts for the magnetic entropy in the paramagnetic state and the number of nearest magnetic neighbors. The experimentally known systems, Fe$_{1-x}$Co$_x$, Fe$_{1-x}$Cr$_x$, Fe$_{1-x}$V$_x$, NiMnSb-based Heusler alloys, Ti$_{1-x}$Cr$_x$N, and Co$_{1-x}$Al$_x$ are investigated. The experimentally unexplored system Fe$_{1-x}$Tc$_x$ is also tested to demonstrate the usefulness of the developed method in guiding future experimental efforts. This work demonstrates the broad applicability of the developed method across various systems, requiring less hands-on adjustments compared to other theoretical approaches.