Excitations and spin correlations near the interface of two three-dimensional Heisenberg antiferromagnets

TL;DR

This paper investigates how magnetic excitations and spin correlations behave near the interface of two three-dimensional Heisenberg antiferromagnets, revealing the emergence of quasi-two-dimensional spin waves and enhanced correlations due to boundary effects.

Contribution

It introduces a detailed analysis of boundary-induced quasi-two-dimensional spin waves and their impact on spin correlations using the spin-wave approximation.

Findings

Quasi-two-dimensional spin waves appear near the boundary when boundary interactions differ.

Boundary modes suppress bulk magnons, creating distinct magnetic regions.

Spin correlations are amplified at the interface due to reduced dimensionality.

Abstract

Magnetic excitations and spin correlations near the interface of two spin-$\frac12$ Heisenberg antiferromagnets are considered using the spin-wave approximation. When the interaction between boundary spins differs essentially from exchange constants inside the antiferromagnets, quasi-two-dimensional spin waves appear in the near-boundary region. They eject bulk magnons from this region, thereby dividing the antiferromagnets into areas with different magnetic excitations. The decreased dimensionality of the near-boundary modes leads to amplified nearest-neighbor spin correlations in the interface area.