Boundary conditions for and ferromagnetic resonance spectra of magnetic bilayers coupled by interlayer Dzyaloshinskii-Moriya interactions

TL;DR

This paper investigates how interlayer Dzyaloshinskii-Moriya interactions uniquely influence ferromagnetic resonance spectra in magnetic bilayers, revealing that IL-DMI affects resonance frequencies and can be experimentally distinguished.

Contribution

The authors derive new boundary conditions for exchange interactions and demonstrate that IL-DMI modifies FMR frequencies, unlike interfacial DMI.

Findings

IL-DMI alters fundamental FMR mode frequencies

Boundary conditions for exchange interactions are newly derived

IL-DMI can be experimentally separated from other effects

Abstract

Interfacial Dzyaloshinskii-Moriya interaction (IF-DMI) leads to non-collinear spin configurations within the magnetic layers of multilayer heterostructures, while its interlayer counterpart (IL-DMI) minimizes chiral states between the layers. Here, we demonstrate that the symmetries of these interactions are very different, even though both arise from pairwise exchange interactions between magnetic sites mediated by nonmagnetic atoms. By deriving new boundary conditions for the exchange operator and solving the associated boundary value problem, we show that, unlike IF-DMI, which does not contribute to the FMR frequencies, IL-DMI alters the frequencies of the fundamental FMR modes and can be separated from other contributions in an FMR experiment.