Exploration of hidden spin polarized electron by high-resolution spin- and angle-resolved photoemission

       As the discovery of high-Tc superconductors promoted the development of high-resolution angular resolved photoelectron spectroscopy (ARPES), recent discovery of new quantum matter, such as topological materials and surface Rashba systems and their peculiar spin-texture of the surface states stimulate to develop high-performance Spin-resolved ARPES (SARPES). Recent high-resolution SARPES measurements that are achieved by high intensity light from the state of the art synchrotron radiation light sources or laser as well as the newly developed high performance spin polarimeters open a new era of surface science using SARPES measurement.

 This spin resolution of SARPES measurement is, of course, powerful tool to confirm the spin polarization of Dirac cone of topological insulators or splitting surface states of Rashba systems. However, the biggest advantage of the SARPES is its ability to explore hidden spin split bands that cannot be resolved by normal ARPES measurement. That is, in some sense the spin resolution can improve the energy and/or angular resolution of the normal ARPES measurement. 

 Here in this presentation, we will present some resent results of SAPRES measurement using ESPRESSO machine[1] which is equipping double VLEED spin detector for high-resolution 3D spin vector analysis[2]. Especially some examples that revealed unknown hidden spin polarized states in well-known or already examined surfaces will be addressed[3,4]. In addition, the observation of local hidden spin polarization in centrosymmetric materials that is revealed by the high resolution SARPES with surface sensitivity of photoemission will be presented [5].


[1] T. Okuda et al., Rev. Sci. Instrum. 82, 103302 (2011).

[2] T. Okuda et al., J. Electron Spectrosc. Relat. Phenomena 201, 23–29 (2015).

[3] K. Taguchi et al., in preparation.

[4] T. Warashina et al., Phys. Rev. B accepted.

[5] S. Wu et al., in pareparation.