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arXiv · 2312.00996

Mössbauer spectroscopy study of the magnetostructural and spin-state transitions in the breathing pyrochlore LiFeCr$_{4}$O$_{8}$

Bo Zhang·Wei Ren·Shengyu Yang·Qifeng Kuang·Da Li·Xin Liu·Anmin Zhang·Hua Pang·Liyun Tang·Liang Qiao·Fashen Li·Zhiwei Li
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Abstract

We report on investigations of the complex magnetostructural and spin-state transitions in the breathing pyrochlore LiFeCr$_{4}$O$_{8}$ by means of magnetization, Mössbauer spectroscopy, and density functional theory (DFT) calculations. Three transitions corresponding to the ferrimagnetic transition at $T_N\sim94$ K, the spin-gap transition at $T_{SG}\sim50$ K, and the magnetostructural transition at $T_{MS}\sim19$ K were observed from the $χ$(T) curve, whereas only $T_N$ and $T_{MS}$ were evidenced for the Fe site from our Mössbauer measurements, suggesting that the spin-gap transition is absent at the Fe site. This indicates that the spin-gap transition is an effect of the breathing Cr$_4$ lattice, in agreement with our DFT calculations from which we see nearly decoupled electronic states for the FeO$_4$ and CrO$_6$ units. From the temperature dependence of the hyperfine magnetic field we also observed a spin-state transition for the Fe spins at $T_{MS}$ consistent with earlier neutron diffraction measurements. These local characteristics are believed to be important for a complete understanding of the complex magnetostructural coupling effects observed in similar systems.

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Bo Zhang, Wei Ren, Shengyu Yang, Qifeng Kuang, Da Li, Xin Liu, Anmin Zhang, Hua Pang, Liyun Tang, Liang Qiao, Fashen Li, Zhiwei Li. 2023-12-02. Mössbauer spectroscopy study of the magnetostructural and spin-state transitions in the breathing pyrochlore LiFeCr$_{4}$O$_{8}$. https://doi.org/10.1103/physrevb.108.214401

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