TY  - JOUR
A1  - Gottscholl, Andreas
A1  - Diez, Matthias
A1  - Soltamov, Victor
A1  - Kasper, Christian
A1  - Krauße, Dominik
A1  - Sperlich, Andreas
A1  - Kianinia, Mehran
A1  - Bradac, Carlo
A1  - Aharonovich, Igor
A1  - Dyakonov, Vladimir
T1  - Spin defects in hBN as promising temperature, pressure and magnetic field quantum sensors
JF  - Nature Communications
N2  - Spin defects in solid-state materials are strong candidate systems for quantum information technology and sensing applications. Here we explore in details the recently discovered negatively charged boron vacancies (V\(_B\)\(^−\)) in hexagonal boron nitride (hBN) and demonstrate their use as atomic scale sensors for temperature, magnetic fields and externally applied pressure. These applications are possible due to the high-spin triplet ground state and bright spin-dependent photoluminescence of the V\(_B\)\(^−\). Specifically, we find that the frequency shift in optically detected magnetic resonance measurements is not only sensitive to static magnetic fields, but also to temperature and pressure changes which we relate to crystal lattice parameters. We show that spin-rich hBN films are potentially applicable as intrinsic sensors in heterostructures made of functionalized 2D materials.
KW  - electronic properties and materials
KW  - qubits
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-261581
VL  - 12
IS  - 1
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  - 
TY  - THES
A1  - Kasper, Christian Andreas
T1  - Engineering of Highly Coherent Silicon Vacancy Defects in Silicon Carbide
T1  - Erzeugung hochkohärenter Silizium Fehlstellen in Siliziumkarbid
N2  - In this work the creation of silicon vacancy spin defects in silicon carbide with predictable properties is demonstrated. Neutron and electron irradiation was used to create silicon vacancy ensembles and proton beam writing to create isolated vacancies at a desired position. The coherence properties of the created silicon vacancies as a function of the emitter density were investigated and a power-law function established. Sample annealing was implemented to increase the coherence properties of existing silicon vacancies. Further, spectral hole burning was used to implement absolute dc-magnetometry.
N2  - In dieser Arbeit wird die Erzeugung von Silizium Fehlstellen in Siliziumkarbid mit vorhersagbaren Eigenschaften nachgewiesen. Neutronen- und Elektronenbestrahlung wurden zur Erzeugung von Ensembles von Silizium Fehlstellen verwendet, während isolierte Fehlstellen an einer gewünschten Position mit Hilfe eines Protonenstrahls erzeugt wurden. Die Kohärenz der erzeugten Silizium Fehlstellen wurde in Abhängigkeit der Emitterdichte untersucht und eine Gesetzmäßigkeit hierfür eingeführt. Um die Kohärenz der Silizium Fehlstellen zu erhöhen, wurden Annealing Experimente durchgeführt. Des Weiteren wurde spektrales Holeburning verwendet, um absolute DC-Magnetometrie nachzuweisen.
KW  - Störstelle
KW  - Siliciumcarbid
KW  - Kohärenz
KW  - Irradiation
KW  - Color Center
KW  - Spin defect
KW  - Bestrahlung
KW  - Farbzentrum
KW  - Spin Defekt
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-237797
ER  -