Theory of carrier-mediated magnonic superlattices

TL;DR

This paper develops a minimal 1D model for collective spin excitations in ferromagnetic superlattices, revealing antiferromagnetic correlations and local minima in magnon dispersion, with potential experimental implications.

Contribution

It introduces a simplified theoretical framework for understanding spin waves in ferromagnetic superlattices, highlighting new features like antiferromagnetic correlations and controllable magnon wavelengths.

Findings

Evidence of antiferromagnetic correlations in long-wave magnons

Presence of local minima in magnonic dispersion

Potential for controlled spin wave excitation

Abstract

We present a minimal one-dimensional model of collective spin excitations in itinerant ferromagnetic superlattices within the regime of parabolic spin-carrier dispersion. We discuss the cases of weakly and strongly modulated magnetic profiles finding evidences of antiferromagnetic correlations for long-wave magnons (especially significant in layered systems), with an insight into the ground state properties. In addition, the presence of local minima in the magnonic dispersion suggests the possibility of (thermal) excitation of spin waves with a relatively well controlled wave length. Some of these features could be experimentally tested in DMS superlattices based on thin doped magnetic layers, acting as natural interfaces between (spin)electronic and magnonic degrees of freedom.