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arXiv · 2412.16130

Cluster spin glass correlations and dynamics in Zn$_{0.5}$Mn$_{0.5}$Te

Sabrina R. Hatt·Camille Shaw·Emma Zappala·Raju Baral·Stuart Calder·Gerald D. Morris·Brenden R. Ortiz·Karine Chesnel·Benjamin A. Frandsen
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Abstract

We present a magnetometry, muon spin relaxation ($\mu$SR), and neutron scattering study of the insulating face-centered-cubic spin glass Zn$_{0.5}$Mn$_{0.5}$Te. The magnetometry and $\mu$SR results confirm a spin freezing transition around $T_f \approx 23$ K, with the spin fluctuation rate decreasing gradually and somewhat inhomogeneously through the sample volume as the temperature decreases toward $T_f$. Characteristic spin correlation times well above $T_f$ are on the order of 10$^{-10}$ s, in line with expectations for a cluster spin glass. Using magnetic pair distribution function (mPDF) analysis and reverse Monte Carlo (RMC) modeling of the magnetic diffuse neutron scattering data, we show that the spin-glass ground state consists of clusters of spins exhibiting short-range-ordered type-III antiferromagnetic correlations, with a locally ordered moment of 3.1(1) $\mu_{\mathrm{B}}$ between nearest-neighbor spins. The type-III correlations decay exponentially as a function of spin separation distance with a correlation length of approximately 5 \AA. The diffuse magnetic scattering and corresponding mPDF show no significant changes across $T_f$, indicating that the dynamically fluctuating short-range spin correlations in the paramagnetic state retain the same basic type-III configuration; the only change apparent from the neutron scattering data is a gradual reduction of the correlation length and locally ordered moment with increasing temperature. Taken together, these results paint a unique and detailed picture of the local magnetic structure and dynamics in Zn$_{0.5}$Mn$_{0.5}$Te and show that this material is best described as a cluster spin glass. In addition, this work showcases a statistical method for extracting diffuse scattering signals from neutron powder diffraction data.

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Sabrina R. Hatt, Camille Shaw, Emma Zappala, Raju Baral, Stuart Calder, Gerald D. Morris, Brenden R. Ortiz, Karine Chesnel, Benjamin A. Frandsen. 2024-12-20. Cluster spin glass correlations and dynamics in Zn$_{0.5}$Mn$_{0.5}$Te. https://doi.org/10.1103/qv69-dv54

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