TY  - JOUR
A1  - Tuan, Dinh Van
A1  - Scharf, Benedikt
A1  - Žutič, Igor
A1  - Dery, Hanan
T1  - Marrying excitons and plasmons in monolayer transition-metal dichalcogenides
JF  - Physical Review X
N2  - Just as photons are the quanta of light, plasmons are the quanta of orchestrated charge-density oscillations in conducting media. Plasmon phenomena in normal metals, superconductors, and doped semiconductors are often driven by long-wavelength Coulomb interactions. However, in crystals whose Fermi surface is comprised of disconnected pockets in the Brillouin zone, collective electron excitations can also attain a shortwave component when electrons transition between these pockets. In this work, we show that the band structure of monolayer transition-metal dichalcogenides gives rise to an intriguing mechanism through which shortwave plasmons are paired up with excitons. The coupling elucidates the origin for the optical sideband that is observed repeatedly in monolayers of WSe\(_2\) and WS\(_2\) but not understood. The theory makes it clear why exciton-plasmon coupling has the right conditions to manifest itself distinctly only in the optical spectra of electron-doped tungsten-based monolayers.
KW  - physics
KW  - excitons
KW  - plasmons
KW  - semiconductors
KW  - spintronics
KW  - valleytronics
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173030
VL  - 7
IS  - 4
ER  - 
TY  - JOUR
A1  - Maaß, Henriette
A1  - Bentmann, Hendrik
A1  - Seibel, Christoph
A1  - Tusche, Christian
A1  - Eremeev, Sergey V.
A1  - Peixoto, Thiago R.F.
A1  - Tereshchenko, Oleg E.
A1  - Kokh, Konstantin A.
A1  - Chulkov, Evgueni V.
A1  - Kirschner, Jürgen
A1  - Reinert, Friedrich
T1  - Spin-texture inversion in the giant Rashba semiconductor BiTeI
JF  - Nature Communications
N2  - Semiconductors with strong spin–orbit interaction as the underlying mechanism for the generation of spin-polarized electrons are showing potential for applications in spintronic devices. Unveiling the full spin texture in momentum space for such materials and its relation to the microscopic structure of the electronic wave functions is experimentally challenging and yet essential for exploiting spin–orbit effects for spin manipulation. Here we employ a state-of-the-art photoelectron momentum microscope with a multichannel spin filter to directly image the spin texture of the layered polar semiconductor BiTeI within the full two-dimensional momentum plane. Our experimental results, supported by relativistic ab initio calculations, demonstrate that the valence and conduction band electrons in BiTeI have spin textures of opposite chirality and of pronounced orbital dependence beyond the standard Rashba model, the latter giving rise to strong optical selection-rule effects on the photoelectron spin polarization. These observations open avenues for spin-texture manipulation by atomic-layer and charge carrier control in polar semiconductors.
KW  - applied physics
KW  - spintronics
KW  - semiconductors
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173769
VL  - 7
ER  - 
TY  - JOUR
A1  - Simin, D.
A1  - Soltamov, V. A.
A1  - Poshakinskiy, A. V.
A1  - Anisimov, A. N.
A1  - Babunts, R. A.
A1  - Tolmachev, D. O.
A1  - Mokhov, E. N.
A1  - Trupke, M.
A1  - Tarasenko, S. A.
A1  - Sperlich, A.
A1  - Baranov, P. G.
A1  - Dyakonov, V.
A1  - Astakhov, G. V.
T1  - All-Optical dc Nanotesla Magnetometry Using Silicon Vacancy Fine Structure in Isotopically Purified Silicon Carbide
JF  - Physical Review X
N2  - We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-\(^{28}\)SiC) and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100  nT/√Hz within a volume of 3×10\(^{−7}\)mm\(^3\) at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radio-frequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3  mm\(^3\), the projection noise limit is below 100  fT/√Hz.
KW  - condensed matter physics
KW  - optoelectronics
KW  - spintronics
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-147682
VL  - 6
ER  -