Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany.
Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany.
Phys Rev Lett. 2015 Dec 31;115(26):266801. doi: 10.1103/PhysRevLett.115.266801. Epub 2015 Dec 23.
Linearly polarized light with an energy of 3.1 eV has been used to excite highly spin-polarized electrons in an ultrathin film of face-centered-tetragonal cobalt to majority-spin quantum well states (QWS) derived from an sp band at the border of the Brillouin zone. The spin-selective excitation process has been studied by spin- and momentum-resolved two-photon photoemission. Analyzing the photoemission patterns in two-dimensional momentum planes, we find that the optically driven transition from the valence band to the QWS acts almost exclusively on majority-spin electrons. The mechanism providing the high spin polarization is discussed by the help of a density-functional theory calculation. Additionally, a sizable effect of spin-orbit coupling for the QWS is evidenced.
已采用能量为 3.1eV 的线性偏振光来激发面心四方钴的超薄薄膜中高度自旋极化的电子，进入来自布里渊区边缘 sp 带的多数自旋量子阱态 (QWS)。自旋分辨和动量分辨的双光子光发射研究了自旋选择性激发过程。通过在二维动量平面上分析光发射图案，我们发现从价带到 QWS 的光驱动跃迁几乎仅对多数自旋电子起作用。借助密度泛函理论计算讨论了提供高自旋极化的机制。此外，还证明了 QWS 的自旋轨道耦合具有相当大的影响。
