Antiferromagnetic resonance in ferroborate NdFe$_3$(BO$_3$)$_4

TL;DR

This study measures antiferromagnetic resonance spectra of NdFe$_3$(BO$_3$)$_4$ across various frequencies and temperatures, revealing magnetic anisotropy, phase transition effects, and nonlinear excitation behaviors at low temperatures.

Contribution

It provides detailed magnetic parameters and demonstrates the impact of phase transitions and nonlinear effects on AFMR in NdFe$_3$(BO$_3$)$_4$.

Findings

Identified easy-plane antiferromagnetic anisotropy.

Determined anisotropy fields and excitation gaps.

Observed phase transition effects on resonance and absorption.

Abstract

The AFMR spectra of the NdFe$_3$(BO$_3$)$_4$ crystal are measured in a wide range of frequencies and temperatures. It is found that by the type of magnetic anisotropy the compound is an "easy-plane" antiferromagnet with a weak anisotropy in the basal plane. The effective magnetic parameters are determined: anisotropy fields $H_{a1}$=1.14 kOe and $H_{a2}$=60 kOe and magnetic excitation gaps $\Delta\nu_1$=101.9 GHz and $\Delta \nu_2$=23.8 GHz. It is shown that commensurate-incommensurate phase transition causes a shift in resonance field and a considerable change in absorption line width. At temperatures below 4.2 K nonlinear regimes of AFMR excitation at low microwave power levels are observed.