YBaCuFeO中的自旋-电荷-晶格耦合：光学性质与第一性原理计算
Spin-charge-lattice coupling in YBaCuFeO: Optical properties and first-principles calculations.
作者信息
Chen H W, Chen Y-W, Kuo J-L, Lai Y C, Chou F C, Du C H, Liu H L
机构信息
Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan.
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan.
出版信息
Sci Rep. 2019 Mar 1;9(1):3223. doi: 10.1038/s41598-019-39031-6.
We combined spectroscopic ellipsometry, Raman scattering spectroscopy, and first-principles calculations to explore the optical properties of YBaCuFeO single crystals. Measuring the optical absorption spectrum of YBaCuFeO at room temperature revealed a direct optical band gap at approximately 1.41 eV and five bands near 1.69, 2.47, 3.16, 4.26, and 5.54 eV. Based on first-principles calculations, the observed optical excitations were appropriately assigned. Analysis of the temperature dependence of the band gap indicated anomalies in antiferromagnetic phase transition at 455 and 175 K. Additionally, a hardening in the frequency of the E phonon mode was observed at 175 K. The value of the spin-phonon coupling constant was 15.7 mRy/Å. These results suggest a complex nature of spin-charge-lattice interactions in YBaCuFeO.
我们结合了椭偏光谱、拉曼散射光谱和第一性原理计算来探究YBaCuFeO单晶的光学性质。在室温下测量YBaCuFeO的光吸收光谱，发现其直接光学带隙约为1.41 eV，并且在1.69、2.47、3.16、4.26和5.54 eV附近有五个能带。基于第一性原理计算，对观察到的光学激发进行了适当的归属。对带隙温度依赖性的分析表明，在455 K和175 K的反铁磁相变中存在异常。此外，在175 K时观察到E声子模式的频率变硬。自旋-声子耦合常数的值为15.7 mRy/Å。这些结果表明YBaCuFeO中自旋-电荷-晶格相互作用具有复杂的性质。
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