Static and Dynamic XY-Like Short-Range Order in a Frustrated Magnet with Exchange Disorder

Published

January 22, 2016

Author(s)

K. A. Ross, J. W. Krizan, Jose Rodriguez Rivera, R. J. Cava, Collin L. Broholm

Abstract

A single crystal of NaCaCo_2Fd7^ was studied using elastic and inelastic neutron scattering. NaCaCo₂F₇ is a newly synthesized A₂B₂X₇ type pyrochlore, hosting magnetic Co²⁺ ions on the Bsite and mixed non-magnetic Na⁺/Ca²⁺ ions on the a A-site. Fluctuating magnetic correlations are present at temperatures well below the antiferromagnetic interaction strength (θ_CW=-140 K). the Q-dependence of the inelastic intensity indicates local XY-like antiferromagnetic clusters at energies below 2.5 meV, and fluctuating collinear antiferromagnetic clusters above this energy. Below the freezing transition at Τ_f=2.4 K, diffuse elastic scattering develops that is consistent with short range XY antiferromagnetism with a correlation length of 16A. The relevant XY states arise from a continuously deformable manifold of states. Contrary to well-known models that produce the same continuous manifold, order-by-disorder does not select an ordered state in NaCCo₃F₇. Instead, we argue that the weak exchange disorder expected to arise from the heterovalant A-site causes the spin system to freeze into short range ordered clusters that explore this manifold spatially and dynamically on long time scales.

Citation

Physical Review B

Volume

93

Issue

1

Pub Type

Journals

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Keywords

Neutron Scattering, Sping Liquids, Magnetic materials, Quantum Criticallity

Citation

Ross, K. , Krizan, J. , Rodriguez Rivera, J. , Cava, R. and Broholm, C. (2016), Static and Dynamic XY-Like Short-Range Order in a Frustrated Magnet with Exchange Disorder, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=918259 (Accessed October 11, 2025)