Magneto-optical Kerr spectroscopy of noble metals
Magneto-optical Kerr spectroscopy of noble metals
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贵金属磁光克尔光谱
DOI：
10.1103/physrevb.96.235132
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发表时间：
2017
影响因子：
3.7
通讯作者：
V. Antonov
中科院分区：
文献类型：
--
作者：
L. Uba;S. Uba;V. Antonov
报道了贵金属Cu、Ag和Au的磁光响应的实验研究和从头算研究。在1.5T的外加磁场下，在0.74- 5.8eV的光子能量范围内，测量了贵金属薄膜的磁光极性克尔效应（MOKE）谱。根据MOKE和在相同能量点测量的光谱精确确定了完整的电导率张量元素集。非对角带内德鲁德型跃迁的重要性明确证明了每个贵金属，并发现是一个重大的贡献所观察到的光谱。结果表明，第一性原理计算使用自旋极化的完全相对论狄拉克线性muffin-tin-orbital方法与GGA+方法的相关效应包括重现实验光谱，并允许解释贵金属的带间跃迁的磁光响应的微观起源。虽然Cu、Ag和Au的能带结构非常相似，但它们的能带宽度和能带的能量位置（特别是在和对称点）却存在着一些明显的差异，这主要是由于贵金属的自旋轨道分裂不同以及和价波函数的空间范围不同。结果发现，在能带位置的微小差异导致显着差异的MO性质的三种贵金属。虽然Au中的自旋-轨道相互作用比Cu中的大大约六倍，并且比Ag中的大大约两倍，但是Au中的克尔旋转的绝对值与Cu中的具有相同的量值，并且与Ag相比小一个数量级。银中尖锐的克尔效应谱峰不是由于电子带间跃迁，而是由于等离子体边缘分裂。的铜，银，和Au的MO光谱的频带分解和带间跃迁负责的光谱中的突出结构被确定。研究发现，贵金属在外磁场中的磁光活动主要来源于费米面“颈”和“腹”附近布里渊区的带间跃迁。
Magneto-optical (MO) response of the noble metals Cu, Ag, and Au in the joint experimental andab initiotheoretical study is reported. The magneto-optical polar Kerr effect (MOKE) spectra of the noble-metal films were measured with the high sensitivity in the applied magnetic field of 1.5 T over the photon energy range 0.74–5.8 eV. Complete set of the optical conductivity tensor elements was determined precisely from the MOKE and the optical spectra measured at the same energy points. The importance of the off-diagonal intraband Drude-type transitions is demonstrated explicitly for each noble metal and found to be a substantial contribution to the observed spectra. It is shown that the first-principles calculations using the spin-polarized fully relativistic Dirac linear-muffin-tin-orbital method with the inclusion of correlation effects by GGA+approach reproduce well the experimental spectra and allow to explain the microscopic origin of the noble metals' magneto-optical response in terms of interband transitions. Although the energy band structures of Cu, Ag, and Au are very similar, there are some distinctive differences in bandwidths and the energy positions of the bands (especially inandsymmetry points), mainly due to different spin-orbit splitting and differences in the spatial extent of, andvalence wave functions of noble metals. It was found that the small differences in the band positions lead to significant differences in the MO properties of three noble metals. Although the spin-orbit interaction in Au is about six times larger than in Cu, and approximately two times larger than in Ag, the absolute value of Kerr rotation in Au is of the same magnitude as in Cu and one order of magnitude smaller as compared to Ag. The sharp Kerr effect spectral peak in Ag is not due to the electronic interband transitions, but rather to the plasma-edge splitting. The band-by-band decomposition of the Cu, Ag, and Au MO spectra is presented and the interband transitions responsible for the prominent structures in the spectra are identified. It has been found that main magneto-optical activity of noble metals in external magnetic field originates from interband transitions at well-defined small-volume regions of Brillouin zone located near the “neck” and “belly” of the Fermi surface.