Structural and spin-glass properties of single crystal J_eff = ½ pyrochlore antiferromagnet NaCdCo₂F₇

Autor(en)

A. Kancko, G. Giester, R. H. Colman

Abstrakt

Weak bond disorder disrupts the expected spin-liquid ground-state of the ideal S = 1/2 Heisenberg pyrochlore antiferromagnet. Here we introduce a single crystal study of the structural and magnetic properties of the bond-disordered pyrochlore NaCdCo₂F₇. The magnetic susceptibility appears isotropic, with a large negative Curie-Weiss temperature (θ_CW = −108(1) K), however no magnetic order is observed on cooling until a spin-glass transition at T_f = 4.0 K. AC-susceptibility measurements show a frequency-dependent shift of the associated cusp in χ’ at T_f, that can be fitted well by the empirical Vogel-Fulcher law. The magnetic moment of μ_eff = 5.4(1) μ_B/Co²⁺ indicates a significant orbital contribution and heat capacity measurements show that down to 1.8 K, well below T_f, only S_mag ∼ 2/3 Rln(2) of the magnetic entropy is recovered, suggestive of residual continued dynamics. Structural and magnetism comparisons are made with the other known members of the NaA’’Co₂F₇ family (A″ = Ca²⁺, Sr²⁺), confirming the expected relationship between spin-glass freezing temperature, and extent of magnetic bond disorder brought about by the size mismatch between A-site ions.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

Charles University Prague

Journal

Physica Scripta

Band

98

ISSN

0031-8949

DOI

https://doi.org/10.1088/1402-4896/acdeb7

Publikationsdatum

07-2023

Peer-reviewed

Ja

ÖFOS 2012

105116 Mineralogie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Atomic and Molecular Physics, and Optics, Mathematical Physics, Condensed Matter Physics

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/b2f177e1-8962-4fac-be00-459dff2131ce