Spin-phonon coupling probed by infrared transmission spectroscopy in the double perovskite Ba$_2$YMoO$_6$
Spin-phonon coupling probed by infrared transmission spectroscopy in the double perovskite Ba$_2$YMoO$_6$
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DOI：
10.1063/1.4798342
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发表时间：
2013-01
期刊：
影响因子：
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通讯作者：
Z. Qu;Y. Zou;Shile Zhang;L. Ling;Lei Zhang;Yuheng Zhang
中科院分区：
文献类型：
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作者：
Z. Qu;Y. Zou;Shile Zhang;L. Ling;Lei Zhang;Yuheng Zhang
在这项工作中，我们用红外透射谱的方法研究了双钙钛矿结构的局域结构变形。300K时，在255.1 cm-1、343.4 cm-1和561.5 cm-1处观察到三个谱带，它们分别与阳离子Ba2+和阴离子YMo6-2之间的运动、Y-O伸缩运动和MoO 6$八面体的伸缩振动有关。由于晶格常数的收缩，这些模式在冷却时继续硬化。当温度降到130K时，自旋单重态二聚体开始形成，在611 cm-1处出现附加声子模，表明MoO$6$八面体发生了局域扭曲。随着温度的进一步降低，其强度增强，峰位保持不变。这些结果表明，自旋单重态二聚体的形成伴随着MoO$6$八面体局域结构扭曲的发生，为双钙钛矿结构Ba2$YMoO$6$中强的自旋-声子耦合提供了证据。
In this work, we investigate the local structural distortion of the double perovskite Ba$_2$YMoO$_6$ by means of infrared transmission spectroscopy. At 300 K, three bands are observed at $\sim$ 255.1 cm$^{-1}$, $\sim$ 343.4 cm$^{-1}$, and $\sim$ 561.5 cm$^{-1}$, which are related to the motion between the cation Ba$^{2+}$ and the anion YMO$_6^{-2}$, the Y-O stretching motion and the stretching vibration of the MoO$_6$ octahedron, respectively. These modes continue to harden upon cooling owing to the shrink of the lattice constant. When the temperature decreases to $T \leq$ 130 K around which the spin singlet dimer begins to form, an additional phonon mode appears at $\sim$ 611 cm$^{-1}$, suggesting the occurrence of local distortion of MoO$_6$ octahedra. With further decrease of the temperature, its intensity enhances and its peak position keeps unchanged. These results indicate that the formation of the spin singlet dimers is accompanied with the occurrence of the local structure distortion of MoO$_6$ octahedra, providing evidence for the strong spin-phonon coupling in the double perovskite Ba$_2$YMoO$_6$.