Researchers from the University of Tokyo, including Takuya Nomoto, Kohei Shinohara, Hikaru Watanabe, and Ryotaro Arita, have developed a new framework for generating and analyzing magnetic structures, which could have significant implications for the energy industry, particularly in the development of advanced magnetic materials for energy storage and conversion.
The team’s approach is inspired by the concept of oriented spin space groups (SSGs). They first generate magnetic structures as totally symmetric representations of an SSG, and then rotate these structures to align with the maximal magnetic space group of the SSG. This results in what they term spin-symmetry-adapted (SSA) structures and oriented SSA structures, respectively. This framework allows for fixed magnetic moment magnitudes on symmetry-equivalent sites and leverages the spin-orbit coupling (SOC)-induced hierarchy of energy scales.
To validate their scheme, the researchers analyzed the MAGNDATA database and found that 77% of the reported structures could be reproduced at the SSG level, with 82% fully reproduced within the oriented SSG scheme. They then performed spin density functional theory calculations for 283 materials, first conducting self-consistent calculations for SSA structures without SOC, followed by fixed-charge calculations including SOC for the descendant oriented SSA structures. The experimental magnetic structures were reproduced as energetically most stable in 82% of cases at the SSG level without SOC and in 76% of cases at the oriented SSG level with SOC.
The researchers found that the fixed-charge scheme enabled accurate evaluation of SOC-induced energy differences at a low computational cost. The characteristic energy scale among oriented SSA structures was found to be only about 0.29 meV per magnetic atom, approximately 300 times smaller than that of distinct SSA structures. These findings demonstrate that the oriented SSG-based enumeration, combined with the two-step calculations for SSA and oriented SSA structures, provides an efficient and robust route for large-scale magnetic-structure prediction.
The practical applications of this research for the energy industry are significant. The ability to predict and analyze magnetic structures accurately and efficiently can aid in the development of advanced magnetic materials for various energy applications, such as magnetic refrigeration, magnetic energy storage, and spintronic devices. These technologies have the potential to improve energy efficiency, reduce energy losses, and enable new forms of energy conversion and storage.
The research was published in the journal Physical Review Materials.
This article is based on research available at arXiv.