Title: Spin-resolved electronic structure of ferroelectric α-GeTe and multiferroic Ge1-xMnxTe,
Abstract: Germanium telluride features special spin-electric effects originating from
spin-orbit coupling and symmetry breaking by the ferroelectric lattice
polarization, which opens up many prospectives for electrically tunable and
switchable spin electronic devices. By Mn doping of the {\alpha}-GeTe host
lattice, the system becomes a multiferroic semiconductor possessing
magnetoelectric properties in which the electric polarization, magnetization
and spin texture are coupled to each other. Employing spin- and angle-resolved
photoemission spectroscopy in bulk- and surface-sensitive energy ranges and by
varying dipole transition matrix elements, we disentangle the bulk, surface and
surface-resonance states of the electronic structure and determine the spin
textures for selected parameters. From our results, we derive a comprehensive
model of the {\alpha}-GeTe surface electronic structure which fits experimental
data and first principle theoretical predictions and we discuss the
unconventional evolution of the Rashba-type spin splitting upon manipulation by
external B- and E-fields.