Electrically and Mechanically Tunable Electron Spins in Silicon Carbide Color Centers

Abstract

The electron spins of semiconductor defects can have complex interactions with their host, particularly in polar materials like SiC where electrical and mechanical variables are intertwined. By combining pulsed spin resonance with ab initio simulations, we show that spin-spin interactions in 4H-SiC neutral divacancies give rise to spin states with a strong Stark effect, sub-10(-6) strain sensitivity, and highly spin-dependent photoluminescence with intensity contrasts of 15%-36%. These results establish SiC color centers as compelling systems for sensing nanoscale electric and strain fields

Polarizing Nuclear Spins in Silicon Carbide

“…The two strongest hyperfine interactions between 29 Si nuclei and neutral divacancies in 4H-SiC are known to be at 12-13 MHz (the Si IIa lattice site, with threefold degeneracy) and 9-10 MHz (the Si IIb lattice site, with sixfold degeneracy), with A zz positive and both hyperfine tensors nearly isotropic [5]. These sites correspond to the Si atoms nearest to the C atoms on which the neutral divacancy's electronic spin density is localized [16] [ Fig. 1(a)].…”

“…They are the hh and kk divacancies in 4H-SiC [4,5], and the hh, k 1 k 1 , and k 2 k 2 divacancies in 6H-SiC [14,42,43], where the h (hexagonal site) and k (quasicubic site) labels represent the inequivalent lattice sites for vacancies in the SiC lattice. The physical structure of the c-axis-oriented PL6 defect in 4H-SiC [10,14,16] is currently undetermined, but a close relationship to the neutral divacancies is indicated by its similar optical and spin resonances [10], radiative lifetimes [16], and hyperfine spectrum (measured here, see Table I). In the GS, these defects are spin triplets (S ¼ 1) with the Hamiltonian PRL 114, 247603 (2015) …”

“…This robust DNP could be applied to initialize quantum memories in quantumcommunication technologies, especially since the color centers are telecom-range emitters, with narrow optical linewidths at low temperatures [16,21,37]. Other applications of DNP, including solid-state nuclear gyroscopes [38,39] and entanglement-enhanced metrological devices [40], can employ SiC's long nuclear spin-lattice relaxation times [27,41] and its amenability to sophisticated growth and device fabrication.…”

“…In this dynamic nuclear polarization (DNP) [27,28] process, the optically pumped polarization of electron spins bound to either neutral divacancy [4,5,8,10,14] or PL6 [10,14,16] color centers is transferred to proximate nuclei via the hyperfine interaction. Optically polarizing nuclei in SiC is experimentally straightforward, requiring only broadband illumination and a small external magnetic field (300-500 G), with which we tune color-center ensembles to their ground-state (GS) or excited-state (ES) spin-level anticrossings (the GSLAC and ESLAC, respectively).…”

“…The D GS and A zz parameters are calculated at T ¼ 0 K, using the method in Ref. [16]. We match the divacancy forms in 6H-SiC with their corresponding spin transitions by comparing the experimentally determined and calculated D GS parameters.…”