Work

Local force method for the ab initio tight-binding model: Effect of spin-dependent hopping on exchange interactions

Year: 2020

Type: article

Abstract: To estimate the Curie temperature of metallic magnets from first principles, we develop a local force method for the tight-binding model having spin-dependent hopping derived from spin-density-functional theory. While spin-dependent hopping is crucial for the self-consistent mapping to the effective spin model, the numerical cost to treat such nonlocal terms in the conventional Green's function scheme is formidably expensive. Here, we propose a formalism based on the kernel polynomial method (KPM), which makes the calculation dramatically efficient. We perform a benchmark calculation for bcc-Fe, fcc-Co, and fcc-Ni and find that the effect of the magnetic nonlocal terms is particularly prominent for bcc-Fe. We also present several local approximations to the magnetic nonlocal terms for which we can apply the Green's function method and reduce the numerical cost further by exploiting the intermediate representation of the Green's function. By comparing the results of the KPM and local methods, we discuss which local method works most successfully. Our approach provides an efficient way to estimate the Curie temperature of metallic magnets with a complex spin configuration.

Source: Physical review. B./Physical review. B

DOI: 10.1103/physrevb.102.014444

Authors: Takuya Nomoto, Takashi Koretsune, Ryotaro Arita

Institutions: The University of Tokyo, Tohoku University, RIKEN Center for Emergent Matter Science

Language: English

Topic: Physics of Superconductivity and Magnetism

Subfield: Condensed Matter Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: Ministry of Education, Culture, Sports, Science and Technology, Japan Society for the Promotion of Science, Japan Science and Technology Agency, Core Research for Evolutional Science and Technology