Download IMPMC_Rashba-effect_Klein

MASTER DE PHYSIQUE ET APPLICATIONS
Spécialité Sciences des Matériaux et Nano-objets
International Nanomat Master Program
Master thesis proposal (M2) 2016-2017
Laboratory :
IMPMC
Institution address : Campus Jussieu
4 place Jussieu
75252 Paris Cedex 05
Laboratory director : Guillaume Fiquet
Internship supervisor : Yannick Klein / Andrea Gauzzi
Phone : 01.44.27.44.56 / 01.44.27.42.16
e-mail: [email protected] / [email protected]
website: www.impmc.upmc.fr/fr/recherche
Techniques in use : Transport under high pressure, quantum oscillations, photoemission spectroscopy
Applicant skills : We are looking for a student that likes experimentation and data analysis
Key words : spin-orbit coupling, magnetotransport, high pressure
Granted internship : yes (compulsory for UPMC lab)
Matisse labex team : yes
Possibility for a thesis : yes
Study of the Rashba spin-orbit interaction in BaNiS2
Novel device concepts for quantum computation and spintronics have emerged from the discovery of the
integer quantum hall effect (QHE) in field-effect transistors and the subsequent fractional QHE, quantum
spin Hall effect and charge antilocalisation. As a consequence, there is an intense search for systems where
the spin degree of freedom can be manipulated without the use of a magnetic field. It has been shown that
the Rashba effect offers this possibility for it splits electronic states with different spin chirality (±1) in
nonmagnetic materials. While strong Rashba splitting have been found either in noncentrosymmetric bulk
crystals made of heavy elements or at surfaces, our team has recently discovered such a large effect in
BaNiS2 (PhD D. Santos-Cottin), a centrosymmetric bulk crystal with a comparatively light active element
(ZNi = 28). The existence of a staggered electric field E at the Ni-site combined to a local inversion
asymmetry of the active layers (see the figure) is at the origin of this interaction. In order to control the
magnitude of the band splitting, two research routes are envisaged:
- The substitution of Ni by the heavier Pd or Pt elements. As a spin-orbit
interaction, the Rashba effect is enhanced for high Z values.
- The application of hydrostatic pressures up to 10 GPa. This will affect
the distance between Ni and the apical sulphur, which is directly linked to
the intensity of E.
During the internship, you will use one of these routes, at choice, and
investigate the electronic properties of the studied single crystals by using
experimental probes such as transport measurements as a function of
temperature (2 K – 400 K), magnetic field (0 – 9 T) and pressure (up to 10
GPa). The band structure will be analysed by using advanced techniques
such as quantum oscillations in pulse fields up to 60 T (Coll. LNCMI Toulouse) or angle resolved
photoemission spectroscopy (Coll. SOLEIL Synchrotron).