Magnetic and spectral properties of multi-sublattice oxides SrY2O4:Er3+ and SrEr2O4

TL;DR

This study investigates the crystal field effects in SrEr2O4, a geometrically frustrated magnet with complex magnetic ordering, using experimental and theoretical methods to understand the behavior of Er3+ ions at different lattice sites.

Contribution

It provides a comprehensive analysis of crystal field parameters for Er3+ ions in SrEr2O4, combining neutron spectroscopy, optical, and EPR measurements, which was not previously done.

Findings

Derived two sets of crystal field parameters fitting all experimental data.

Identified the effects of inequivalent Er3+ sites on magnetic properties.

Enhanced understanding of magnetic frustration in SrEr2O4.

Abstract

SrEr2O4 is a geometrically frustrated magnet which demonstrates rather unusual properties at low temperatures including a coexistence of long- and short-range magnetic order, characterized by two different propagation vectors. In the present work, the effects of crystal fields (CF) in this compound containing four magnetically inequivalent erbium sublattices are investigated experimentally and theoretically. We combine the measurements of the CF levels of the Er3+ ions made on a powder sample of SrEr2O4 using neutron spectroscopy with site-selective optical and electron paramagnetic resonance measurements performed on single crystal samples of the lightly Er-doped nonmagnetic analogue, SrY2O4. Two sets of CF parameters corresponding to the Er3+ ions at the crystallographically inequivalent lattice sites are derived which fit all the available experimental data well, including the magnetization and dc susceptibility data for both lightly doped and concentrated samples.