GeTe(111): direct evidence of static displacive ferroelectric response coupled to fully spin polarized bulk states

*J. Krempaský (1), G. Springholz (2), J. Minár (3), M. Muntwiler (1), J. H. Dil (1,4)
(1) Photon Science Division, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland, (2) Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria, (3) New Technologies-Research Center University of West Bohemia, Pilsen, Czech Republic, (4) Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

Manipulating spin textures through electric fields is a timely issue due to the potential for applications in low power electronics. Recently, a novel class of ferroelectric materials combining ferroelectric order with Rashba type switching of spin textures at room temperatures [1-3] opened an intriguing route for a non-volatile static electrical control of the spin degrees of freedom. In this respect, GeTe(111) is a model system which appears to possess an extra bonus: fully spin-polarized bulk states. We extended the experimental verification of the ferroelectric switching of these fully spin-polarized states in spin and momentum-resolved ways [3] with operando x-ray photoelectron-diffraction experiments [4]. We found that the ferroelectric response feature systematic displacive response with characteristic fatigue effects consistent with operando spin-resolved measurements [3], proving that static electric fields indeed couple to GeTe domain polarizations and thus to Rashba-type splitting.

[1] D. Di Sante et al., Electric Control of the Giant Rashba Effect in Bulk GeTe, Adv. Mater. (2012).

[2] J. Krempaský et al., Disentangling bulk and surface Rashba effects in ferroelectric α-GeTe, PRB 94, 205111 (2016).

[3] J. Krempaský et al., Operando imaging of all-electric spin texture manipulation in ferroelectric and multiferroic Rashba semiconductors, PRX 8, 021067 (2018).

[4] J. Krempaský et al., in preparation