Elmers H J, Kutnyakhov D, Chernov S V, Medjanik K, Fedchenko O, Zaporozhchenko-Zymakova A, Ellguth M, Tusche C, Viefhaus J, Schönhense G
Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany.
J Phys Condens Matter. 2017 Jun 28;29(25):255001. doi: 10.1088/1361-648X/aa7173. Epub 2017 May 24.
Spin-momentum locking of surface states has attracted great interest in recent years due to envisioned technological applications in the field of spintronics. Normal metal surfaces like W(1 1 0) and Ir(1 1 1) show surface states with energy dispersions and spin-polarization textures, which are reminiscent of topologically non-trivial surface states. In order to understand this phenomenon the connection of bulk and surface states has to be explored. Using time-of-flight momentum microscopy with soft x-ray excitation, we present a comprehensive analysis of the bulk bands of W and Ir. Surface states are determined by the same method with photon excitation in the vacuum ultraviolet region. The superposition of both spectral densities reveals the hosting of surface states within the gap structure of bulk bands projected on the surface Brillouin zone. Quantitative differences in the extension of experimental and theoretical local band gaps indicate an underestimation of electron correlation effects in theory.
近年来，由于自旋电子学领域的潜在技术应用，表面态的自旋动量锁定引起了人们极大的兴趣。像W(1 1 0)和Ir(1 1 1)这样的普通金属表面表现出具有能量色散和自旋极化纹理的表面态，这让人联想到拓扑非平凡表面态。为了理解这一现象，必须探索体态与表面态之间的联系。利用软X射线激发的飞行时间动量显微镜，我们对W和Ir的体态能带进行了全面分析。表面态通过在真空紫外区域的光子激发用相同方法确定。两种光谱密度的叠加揭示了表面态在投影到表面布里渊区的体态能带隙结构中的存在。实验和理论局部带隙扩展的定量差异表明理论上对电子关联效应的低估。
