ELFT HÍRADÓ

[Dr. Széchenyi Gábor <gabor.szechenyi AT ttk.elte.hu>]

Dear Colleagues,

This Tuesday (tomorrow) Rohit Babar is giving a talk at  the ELTE Quantum 
seminar:

Rohit Babar (Department of Physics, Chemistry and Biology, Linköping 
University)
Spin centers in boron nitride and silicon carbide for quantum technology 
applications

Location: 5.128  ELTE TTK (1117 Budapest, Pázmány Péter sétány 1/A)
Time: May 17, Tuesday, 12:00
Abstract: see below.

Best regards,
Gábor Széchenyi

Spin centers in wide-bandgap semiconductors have emerged as promising 
candidates for quantum communication, storage, and sensing applications. The 
spin centers typically comprise of optically active intrinsic defects or 
dopant atoms in semiconducting host, with the feasibility of spin coherent, 
bright emission, and stable operation determined by the spin center-host 
interactions.[1] The emergence of spin centers in two-dimensional host 
represents a new milestone in nanoscale sensing as the increased proximity to 
source could lead to high resolution sensors.[2] In this talk, I will present 
the first-principles study of novel spin centers in hexagonal boron nitride 
(hBN). We investigate the stability and magneto-optical properties of boron 
vacancy pair in the neutral charge state.[3] This spin center is optically 
addressable with a long-lived memory, and can serve as a sensor with an 
efficient coherence protection scheme within a dense nuclear spin 
environment. Similarly, the tetramer carbon clusters in hBN are identified as 
potential spin centers with zero phonon line emission in the visible spectral 
range.
Among bulk semiconductors, the mature growth and implantation techniques for 
silicon carbide (SiC) have led to controlled generation of spin centers. The 
negatively charged silicon vacancy in 4H-SiC is a widely reported spin center 
however the source of electron paramagnetic resonance and photoluminescence 
measurements close to the vacancy remains unknown. Based on our combined 
theory and experiment investigation, we attribute these signals to silicon 
vacancy perturbed by neighboring carbon antisite.[4] Lastly, we demonstrate 
the modification of spin center properties in the presence of an extended 
defect. For the divacancy-stacking fault complex in 4H-SiC, the distinct 
divacancy configurations within the stacking fault show a large zero-field 
splitting. This could potentially lead to development of robust spin centers 
by further improving the coherence protection scheme achieved for basal 
divacancies in 4H-SiC.

[1] G. Wolfowicz, et al., Nat. Rev. Mat. 6, 906 (2021)
[2] A. Gottscholl, et al., Nat. Commun. 12, 4480 (2021)
[3] R. Babar, et al., arXiv:2111.09589 (2021)
[4] J. Davidsson, et al., in preparation (2022)