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The breaking of bulk inversion symmetry in ferroelectric semiconductors causes a Rashba-type spin splitting of electronic bulk bands. This is shown by a comprehensive mapping of the spin polarization of the electronic bands in ferroelectric α-GeTe (111) films using a time-of-flight momentum microscope equipped with an imaging spin filter that enables a simultaneous measurement of more than 10 000 data points. The experiment reveals an opposite spin helicity of the inner and outer Rashba bands with a different spin polarization in agreement with theoretical predictions, confirming a complex spin texture of bulk Rashba states. The outer band has about twice larger spin polarization than the inner one, giving evidence of a spin-orbit effect being related to the orbital composition of the band states. The switchable inner electric field of GeTe implies new functionalities for spintronic devices.
American Physical Society
Publication date: 
9 Nov 2016

Hans Joachim Elmers, Robert Wallauer, Marcus Liebmann, Jens Kellner, Markus Morgenstern, RN Wang, Jos E Boschker, Raffaella Calarco, Jaime Sánchez-Barriga, Oliver Rader, Dmytro Kutnyakhov, Sergey V Chernov, Katerina Medjanik, Christian Tusche, Martin Ellguth, H Volfova, J Braun, J Minár, H Ebert, G Schönhense

Biblio References: 
Volume: 94 Issue: 20 Pages: 201403
Physical Review B