Determination of magnetic order of the rare-earth ions in multiferroic TbMn2O5

TL;DR

This study uses resonant x-ray magnetic scattering to investigate the magnetic order of rare-earth ions in multiferroic TbMn2O5, revealing detailed spin orientations and polarization states across different phases.

Contribution

It provides the first detailed analysis of terbium ion magnetic order in TbMn2O5 using polarization analysis at multiple resonances.

Findings

Confirmed terbium valence state polarization by Mn4+ spin density

Refined terbium spin orientations in different phases

Identified distinct resonances for 5d and 4f bands

Abstract

We have employed resonant x-ray magnetic scattering to specifically probe the magnetic order of the rare-earth ions in multiferroic $\mathrm{TbMn_2O_5}$. Two energy resonances were observed, one originated from the E1-E1 dipolar transition and the other from the E2-E2 quadrupolar transition. These resonances directly probe the valence 5d band and the partially occupied 4f band, respectively. First, full polarization analysis, which is a measurement of the scattered polarization as a function of incident polarization, confirmed a spin polarization of the terbium valence states (probed by the E1-E1 transition) by the $\mathrm{Mn^{4+}}$ spin density in the commensurate phase. Second, full polarization analysis data were collected in the low-temperature incommensurate and commensurate phases when tuned to the E2-E2 resonance. By employing a least-squares fitting procedure, the spin orientations of the terbium ion sublattice were refined.