Ordering of localized electronic states in multiferroic TbMnO3: a soft X-ray resonant scattering study

TL;DR

This study uses soft X-ray resonant scattering to directly observe the ordering of localized electronic states on Mn and Tb sites in multiferroic TbMnO3, revealing temperature-dependent magnetic and ferroelectric orderings.

Contribution

First direct observation of localized electronic state ordering in TbMnO3 using soft X-ray resonant scattering at Mn and Tb edges.

Findings

Mn 3d sublattice shows long-range order between 28 K and 42 K

Tb 4f sublattice orders below 28 K in the ferroelectric/magnetic phase

Resonant enhancement occurs at Mn L and Tb M edges

Abstract

Soft X-ray resonant scattering (XRS) has been used to observe directly, for the first time, the ordering of localized electronic states on both the Mn and Tb sites in multiferroic TbMnO$_3$. Large resonant enhancement of the X-ray scattering cross-section were observed when the incident photon energy was tuned to either the Mn $L$ or Tb $M$ edges which provide information on the Mn 3d and Tb $4f$ electronic states, respectively. The temperature dependence of the XRS signal establishes, in a model independent way, that in the high-temperature phase (28 K $\leq$ T $\leq$ 42 K) the Mn 3d sublattices displays long-range order. The Tb $4f$ sublattices are found to order only on entering the combined ferroelectric/magnetic state below 28 K. Our results are discussed with respect to recent hard XRS experiments (sensitive to spatially extended orbitals) and neutron scattering.