Abstract
The spin-resolved electronic band structure of Au-induced metallic atomic wires on a vicinal silicon surface, Si(553), was investigated using spin- and angle-resolved photoelectron spectroscopy. We directly measured the spin polarization of three partially filled one-dimensional metallic bands, a one-third-filled band, and the doublet of nearly half-filled bands. For the half-filled doublet, the strong apparent spin polarization was observed near the Fermi energy with a minor out-of-plane spin component. This observation is consistent with the Rashba-type spin-orbit splitting and with a recent experiment on a similar doublet of Si(557)-Au. In contrast, the one-third-filled band does not show a substantial spin polarization within the experimental accuracy, indicating a much smaller spin splitting, if any. These results are discussed for the origin of the partially filled bands and for the intriguing broken-symmetry ground state observed at low temperature.
Highlights
Spintronics is seeking high performance electronic devices that exploit the spin degree of freedom of electrons [1]
Scanning tunneling microscopy (STM) and angle-resolved photoelectron spectroscopy (ARPES) studies showed the formation of regular atomic wire arrays along step edges and 1D electronic structures with multiple metallic bands, respectively [11,12,13]
The spin- and angle-resolved photoelectron spectroscopy (SARPES) measurements were performed at Hiroshima Synchrotron Radiation Center using undulator radiation (34 eV) using a high-resolution SARPES machine (ESPRESSO), which combines a high-performance hemispherical electron analyzer with two efficient spin detectors based on very-low-energy-electron diffraction from a magnetized target [29]
Summary
Spintronics is seeking high performance electronic devices that exploit the spin degree of freedom of electrons [1]. A few materials systems with strong SOC, for recent examples, such as topological insulators [3] and heavy metal thin films [4, 5], were proposed as candidates for such spintronic applications In these materials, the spin polarization emerges without external magnetic fields, even at room temperature, through the quantum spin Hall effect or the Rashba spin splitting of surface-state bands. Scanning tunneling microscopy (STM) and angle-resolved photoelectron spectroscopy (ARPES) studies showed the formation of regular atomic wire arrays along step edges and 1D electronic structures with multiple metallic bands, respectively (see figure 1 for the atomic structure model schematics and the band structure) [11,12,13] These systems share two closely lying nearly half-filled bands [12, 14,15,16], whose origin has been under debate. The implications of the present results for atomic origins of the 1D metallic bands, the structure models proposed recently, and the broken-symmetry ground states at low temperature are discussed
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