Mössbauer spectroscopy study of magnetostructural and spin-state transitions in the breathing pyrochlore LiFeCr4O8</mml:ms
Mössbauer spectroscopy study of magnetostructural and spin-state transitions in the breathing pyrochlore LiFeCr4O8</mml:ms
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DOI：
10.1103/physrevb.108.214401
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发表时间：
2023-12
影响因子：
3.7
通讯作者：
Bo Zhang;Wei Ren;Shengyu Yang;Qifeng Kuang;Da Li;Xin Liu;Anmin Zhang;H. Pang;Liyun Tang;Liang Qiao;Fashen Li;Zhiwei Li
中科院分区：
文献类型：
--
作者：
Bo Zhang;Wei Ren;Shengyu Yang;Qifeng Kuang;Da Li;Xin Liu;Anmin Zhang;H. Pang;Liyun Tang;Liang Qiao;Fashen Li;Zhiwei Li
我们报告了通过磁化、M\"ossbauer 光谱和密度泛函理论 (DFT) 计算对呼吸烧绿石 LiFeCr$_{4}$O$_{8}$ 中复杂的磁结构和自旋态转变的研究。三个转变对应于 $T_N\sim94$ K 处的亚铁磁转变、$T_{SG}\sim50$ K 处的自旋间隙转变和磁结构转变从 $\chi$(T) 曲线观察到在 $T_{MS}\sim19$ K 处，而从我们的 M\"ossbauer 测量中仅发现 $T_N$ 和 $T_{MS}$ 存在 Fe 位点，这表明 Fe 位点不存在自旋能隙跃迁。这表明自旋能隙跃迁是呼吸 Cr$_4$ 晶格的影响，与我们的 DFT 计算一致，从中我们看到 FeO$_4$ 和 CrO$_6$ 单元的电子态几乎解耦。根据超精细磁场的温度依赖性，我们还观察到 $T_{MS}$ 处 Fe 自旋的自旋态转变，与早期的中子衍射测量一致。这些局部特征被认为对于完整理解在类似系统中观察到的复杂磁结构耦合效应非常重要。
We report on investigations of the complex magnetostructural and spin-state transitions in the breathing pyrochlore LiFeCr$_{4}$O$_{8}$ by means of magnetization, M\"ossbauer 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 $\chi$(T) curve, whereas only $T_N$ and $T_{MS}$ were evidenced for the Fe site from our M\"ossbauer 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.