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Dynamical magnetic susceptibility of non-collinear magnets: A novel KKR-based ab initio scheme and its application

David Eilmsteiner, Arthur Ernst, Paweł A. Buczek

Abstract

A novel implementation of the linear response time-dependent density functional theory addressing spin excitations in non-collinear magnets based on the Korringa-Kohn-Rostoker Green's function method is presented. Following the exposition of the formalism based on the adiabatic local spin density approximation to the exchange-correlation kernel generalized to the non-collinear case, the computational scheme is discussed in detail. The formation of the Goldstone modes in non-collinear susceptibility calculations is elaborated on formally and from the numerical convergence point of view. The scheme is deployed to study the dispersion, Landau damping, and spatial shapes of magnons for the representative members of the kagome non-collinear antiferromagnets.

Dynamical magnetic susceptibility of non-collinear magnets: A novel KKR-based ab initio scheme and its application

Abstract

A novel implementation of the linear response time-dependent density functional theory addressing spin excitations in non-collinear magnets based on the Korringa-Kohn-Rostoker Green's function method is presented. Following the exposition of the formalism based on the adiabatic local spin density approximation to the exchange-correlation kernel generalized to the non-collinear case, the computational scheme is discussed in detail. The formation of the Goldstone modes in non-collinear susceptibility calculations is elaborated on formally and from the numerical convergence point of view. The scheme is deployed to study the dispersion, Landau damping, and spatial shapes of magnons for the representative members of the kagome non-collinear antiferromagnets.
Paper Structure (13 sections, 53 equations, 1 figure)

This paper contains 13 sections, 53 equations, 1 figure.

Table of Contents

  1. Introduction
  2. Formalism
  3. Generalized susceptibility
  4. Linear response time dependent density function theory formulation
  5. Exchange-correlation kernel
  6. The emergence of the Goldstone modes in non-collinear magnets
  7. Implementation
  8. Korringa-Kohn-Rostoker Green's function method
  9. Evaluation of susceptibility
  10. Magnons of IrMn$_3$
  11. Summary and discussion
  12. Källén-Lehmann spectral representation and the fluctuation-dissipation theorem
  13. The symbolic handling of the spin matrix traces

Figures (1)

  • Figure 1: Magnon-spectrum within the 2D Brillouin zone, i.e. magnons propagating in the 111-lattice plane. Error bars inform about the FWHM of the magnon peak, i.e. the inverse lifetime. On the right, the 2D Fermi surface is shown together with the path through the Brillouin zone.