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  - 
TY  - JOUR
A1  - Anisimov, A. N.
A1  - Simin, D.
A1  - Soltamov, V. A.
A1  - Lebedev, S. P.
A1  - Baranov, P. G.
A1  - Astakhov, G. V.
A1  - Dyakonov, V.
T1  - Optical thermometry based on level anticrossing in silicon carbide
JF  - Scientific Reports
N2  - We report a giant thermal shift of 2.1 MHz/K related to the excited-state zero-field splitting in the silicon vacancy centers in 4H silicon carbide. It is obtained from the indirect observation of the optically detected magnetic resonance in the excited state using the ground state as an ancilla. Alternatively, relative variations of the zero-field splitting for small temperature differences can be detected without application of radiofrequency fields, by simply monitoring the photoluminescence intensity in the vicinity of the level anticrossing. This effect results in an all-optical thermometry technique with temperature sensitivity of 100 mK/Hz\(^{1/2}\) for a detection volume of approximately 10\(^{−6}\) mm\(^3\). In contrast, the zero-field splitting in the ground state does not reveal detectable temperature shift. Using these properties, an integrated magnetic field and temperature sensor can be implemented on the same center.
KW  - electronic and spintronic devices
KW  - electronic properties and materials
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-147809
VL  - 6
IS  - 33301
ER  - 
TY  - JOUR
A1  - Astakhov, Georgy V.
A1  - Fuchs, F.
A1  - Soltamov, V. A.
A1  - Väth, S.
A1  - Baranov, P. G.
A1  - Mokhov, E. N.
A1  - Dyakonov, V.
T1  - Silicon carbide light-emitting diode as a prospective room temperature source for single photons
JF  - Scientific Reports
N2  - Generation of single photons has been demonstrated in several systems. However, none of them satisfies all the conditions, e.g. room temperature functionality, telecom wavelength operation, high efficiency, as required for practical applications. Here, we report the fabrication of light-emitting diodes (LEDs) based on intrinsic defects in silicon carbide (SiC). To fabricate our devices we used a standard semiconductor manufacturing technology in combination with high-energy electron irradiation. The room temperature electroluminescence (EL) of our LEDs reveals two strong emission bands in the visible and near infrared (NIR) spectral ranges, associated with two different intrinsic defects. As these defects can potentially be generated at a low or even single defect level, our approach can be used to realize electrically driven single photon source for quantum telecommunication and information processing.
KW  - semiconductors
KW  - inorganic LEDs
KW  - quantum optics
KW  - nanophotonics
KW  - plasmonics
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96308
ER  - 
TY  - JOUR
A1  - Astakhov, Georgy V.
A1  - Kraus, Hannes
A1  - Soltamov, V. A.
A1  - Fuchs, Franziska
A1  - Simin, Dimitrij
A1  - Sperlich, Andreas
A1  - Baranov, P. G.
A1  - Dyakonov, Vladimir
T1  - Magnetic field and temperature sensing with atomic-scale spin defects in silicon carbide
N2  - Quantum systems can provide outstanding performance in various sensing applications, ranging from bioscience to nanotechnology. Atomic-scale defects in silicon carbide are very attractive in this respect because of the technological advantages of this material and favorable optical and radio frequency spectral ranges to control these defects. We identified several, separately addressable spin-3/2 centers in the same silicon carbide crystal, which are immune to nonaxial strain fluctuations. Some of them are characterized by nearly temperature independent axial crystal fields, making these centers very attractive for vector magnetometry. Contrarily, the zero-field splitting of another center exhibits a giant thermal shift of −1.1 MHz/K at room temperature, which can be used for thermometry applications. We also discuss a synchronized composite clock exploiting spin centers with different thermal response.
KW  - condensed-matter physics
KW  - quantum physics
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-113025
ER  - 
TY  - JOUR
A1  - Fuchs, F.
A1  - Stender, B.
A1  - Trupke, M.
A1  - Simin, D.
A1  - Pflaum, J.
A1  - Dyakonov, V.
A1  - Astakhov, G.V.
T1  - Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide
JF  - Nature Communications
N2  - Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.
KW  - nuclear magnetic resonance
KW  - coherent control
KW  - 4H
KW  - phosphorus
KW  - qubits
KW  - defects
KW  - entanglement
KW  - room temperature
KW  - vacancy
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148502
VL  - 6
IS  - 7578
ER  - 
TY  - JOUR
A1  - Baumann, A.
A1  - Tvingstedt, K.
A1  - Heiber, M. C.
A1  - Väth, S.
A1  - Momblona, C.
A1  - Bolink, H. J.
A1  - Dyakonov, V.
T1  - Persistent photovoltage in methylammonium lead iodide perovskite solar cells
JF  - APL Materials
N2  - We herein perform open circuit voltage decay (OCVD) measurements on methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to increase the understanding of the charge carrier recombination dynamics in this emerging technology. Optically pulsed OCVD measurements are conducted on CH3NH3PbI3 solar cells and compared to results from another type of thin-film photovoltaics, namely, the two reference polymer–fullerene bulk heterojunction solar cell devices based on P3HT:PC60BM and PTB7:PC70BM blends. We observe two very different time domains of the voltage transient in the perovskite solar cell with a first drop on a short time scale that is similar to the decay in the studied organic solar cells. However, 65%–70% of the maximum photovoltage persists on much longer timescales in the perovskite solar cell than in the organic devices. In addition, we find that the recombination dynamics in all time regimes are dependent on the starting illumination intensity, which is also not observed in the organic devices. We then discuss the potential origins of these unique behaviors.
KW  - solar cells
KW  - illumination
KW  - dielectric oxides
KW  - carrier density
KW  - bioelectrochemistry
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119397
VL  - 2
IS  - 8
ER  - 
TY  - JOUR
A1  - Gottscholl, Andreas
A1  - Wagenhöfer, Maximilian
A1  - Klimmer, Manuel
A1  - Scherbel, Selina
A1  - Kasper, Christian
A1  - Baianov, Valentin
A1  - Astakhov, Georgy V.
A1  - Dyakonov, Vladimir
A1  - Sperlich, Andreas
T1  - Superradiance of spin defects in silicon carbide for maser applications
JF  - Frontiers in Photonics
N2  - Masers as telecommunication amplifiers have been known for decades, yet their application is strongly limited due to extreme operating conditions requiring vacuum techniques and cryogenic temperatures. Recently, a new generation of masers has been invented based on optically pumped spin states in pentacene and diamond. In this study, we pave the way for masers based on spin S = 3/2 silicon vacancy (V\(_{Si}\)) defects in silicon carbide (SiC) to overcome the microwave generation threshold and discuss the advantages of this highly developed spin hosting material. To achieve population inversion, we optically pump the V\(_{Si}\) into their m\(_S\) = ±1/2 spin sub-states and additionally tune the Zeeman energy splitting by applying an external magnetic field. In this way, the prerequisites for stimulated emission by means of resonant microwaves in the 10 GHz range are fulfilled. On the way to realising a maser, we were able to systematically solve a series of subtasks that improved the underlying relevant physical parameters of the SiC samples. Among others, we investigated the pump efficiency as a function of the optical excitation wavelength and the angle between the magnetic field and the defect symmetry axis in order to boost the population inversion factor, a key figure of merit for the targeted microwave oscillator. Furthermore, we developed a high-Q sapphire microwave resonator (Q ≈ 10\(^4\)–10\(^5\)) with which we find superradiant stimulated microwave emission. In summary, SiC with optimized spin defect density and thus spin relaxation rates is well on its way of becoming a suitable maser gain material with wide-ranging applications.
KW  - stimulated emission
KW  - maser
KW  - population inversion
KW  - silicon vacancy
KW  - spin polarization
KW  - superradiance
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284698
SN  - 2673-6853
VL  - 3
ER  -