Evaluating the Effects of Structural Disorder on the Magnetic Properties of Nd2Zr2O7

Published

August 9, 2021

Author(s)

Eli Zoghlin, Julian Schmehr, Collin Holgate, Rebecca Dally, Yaohua Liu, Geneva Laurita, Stephen Wilson

Abstract

Motivated by the variation in reported lattice parameters of floating-zone-grown Nd₂Zr₂O₇ crystals, we have performed a detailed study of the relationship between synthesis environment, structural disorder, and magnetic properties. Using a combination of polycrystalline standards, electron-probe microanalysis and scattering techniques, we show that crystals grown under atmospheric conditions have a reduced lattice parameter (relative to pristine polycrystalline powders) due to occupation of the Nd-site by excess Zr (i.e. "negative" stuffing). In contrast, crystals grown under high-pressure Ar are nearly stoichiometric with an average lattice parameter approaching the polycrystalline value. While minimal disorder of the oxygen sublattices is observed on the scale of the average structure, neutron pair-distribution function analysis indicates a highly local disorder of the oxygen coordination, which is only weakly dependent on growth environment. Most importantly, our magnetization, heat capacity and single-crystal neutron scattering data show that the magnetic properties of crystals grown under high-pressure Ar match closely with those of stoichiometric powders. The neutron scattering measurements reveal that the signature of magnetic moment fragmentation – the coexistence of "all-in-all-out" (AIAO) magnetic Bragg peaks and diffuse pinch-point scattering due to spin-ice correlations - persists in these nearly stoichiometric crystals. However, in addition to an increased AIAO transition temperature, the diffuse signal remains significant to higher temperatures than previously reported. This behavior indicates that both the AIAO magnetic order and the spin-ice correlations are sensitive to deviations of the Nd stoichiometry.

Citation

Physical Review Materials

Volume

5

Issue

8

Pub Type

Journals

Keywords

neutron scattering, pyrochlore, magnetism, floating zone, diffuse scattering, magnetic moment fragmentation

Citation

Zoghlin, E. , Schmehr, J. , Holgate, C. , Dally, R. , Liu, Y. , Laurita, G. and Wilson, S. (2021), Evaluating the Effects of Structural Disorder on the Magnetic Properties of Nd₂Zr₂O₇, Physical Review Materials (Accessed April 25, 2024)