High dynamic nuclear polarization at room temperature

Henstra, A.; Lin, Tien‐Sung; Schmidt, Jan; Wenckebach, W.Th.

doi:10.1016/0009-2614(90)87002-9

Cited by 160 publications

(163 citation statements)

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“…In this case, the problem was circumvented by directly generating electron spin polarization at the defect centre via resonant optical excitation of the localized states without involvement of conduction-band electrons 12 and thereby removing the restriction imposed by strong conductionband electron spin relaxation. Further extending to solids in general, perhaps the only other exceptional case when RT DNP was possible is the polarization transfer from the photo-excited triplet state of the guest pentacene molecule to the protons of the naphthalene host molecular crystal 24 . A similar approach to the nitrogen-vacancy centre in diamond was used, namely by resonant optical excitation of localized electron spin state.…”

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confidence: 99%

Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor

et al. 2013

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Nuclear spin hyperpolarization is essential to future solid-state quantum computation using nuclear spin qubits and in highly sensitive magnetic resonance imaging. Though efficient dynamic nuclear polarization in semiconductors has been demonstrated at low temperatures for decades, its realization at room temperature is largely lacking. Here we demonstrate that a combined effect of efficient spin-dependent recombination and hyperfine coupling can facilitate strong dynamic nuclear polarization of a defect atom in a semiconductor at room temperature. We provide direct evidence that a sizeable nuclear field (B150 Gauss) and nuclear spin polarization (B15%) sensed by conduction electrons in GaNAs originates from dynamic nuclear polarization of a Ga interstitial defect. We further show that the dynamic nuclear polarization process is remarkably fast and is completed in o5 ms at room temperature. The proposed new concept could pave a way to overcome a major obstacle in achieving strong dynamic nuclear polarization at room temperature, desirable for practical device applications.

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Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor

et al. 2013

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“…(1), these side peaks are at frequencies f 0 AE A zz =2, where A zz is the c-axis projection of the hyperfine interaction between the electron spin and a nearby nucleus. 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.…”

Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

“…We define the degree of nuclear spin polarization (P) as P ¼ ðI þ − I − Þ=ðI þ þ I − Þ, where I þ and I − , respectively, represent the populations of 29 Si-nuclear spins pointing ↑ and ↓ [32]. P is defined separately for each pairing of inequivalent defect form with inequivalent 29 Si site. We quantify P by performing a global fit the ODMR line shapes to the sum of seven Lorentzians, one centered at f 0 and one pair at each of the Si IIa , Si IIb , and C II hyperfine resonances ( [44]).…”

Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

“…In this Letter, we show that near-infrared light can nearly completely polarize populations of 29 Si nuclear spins in SiC. 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.…”

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confidence: 92%

“…At elevated temperatures, the form of the ES Hamiltonian is similar to that of the GS, with g ES substituting for g GS , D ES substituting for D GS , and A j;ES substituting for A j;GS . Silicon's dominant isotope is 28 Si, with zero nuclear spin, but the spin-1=2 isotope 29 Si also has a fairly high natural abundance of 4.7%. We denote the state of a hyperfinecoupled spin pair as jm S ; m I i, where m S ∈ f−1; 0; 1g is the electronic spin state and m I ∈ f↑; ↓g is the 29 Si nuclear spin state.…”

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Polarizing Nuclear Spins in Silicon Carbide

Cappellaro

2015

Physics

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We demonstrate optically pumped dynamic nuclear polarization of 29 Si nuclear spins that are strongly coupled to paramagnetic color centers in 4H-and 6H-SiC. The 99% AE 1% degree of polarization that we observe at room temperature corresponds to an effective nuclear temperature of 5 μK. By combining ab initio theory with the experimental identification of the color centers' optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging. DOI: 10.1103/PhysRevLett.114.247603 PACS numbers: 76.70.Fz, 61.72.jn, 71.55.-i, 76.30.Mi Silicon carbide is a promising material for quantum electronics at the wafer scale. It is both an industrially important substrate for high-performance electronic devices [1] and a host to several types of vacancy-related paramagnetic color centers with remarkable attributes . Much like the diamond nitrogen-vacancy center [24,25], these color centers have electronic spin states that can be addressed at either ensemble or single-spin levels [18,19] through optically detected magnetic resonance (ODMR). Moreover, spin coherence times can exceed 1 ms [18], and ODMR can persist up to room temperature [10,11,14,19]. Although the fluctuating nuclear spin bath is a principal source of electronic spin decoherence in these types of systems [26], nuclear spins in SiC are not purely detrimental. If polarized and controlled, they would be a technologically valuable resource.In this Letter, we show that near-infrared light can nearly completely polarize populations of 29 Si nuclear spins in SiC. 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). Optically pumping crystals has previously led to roomtemperature DNP in napthalene [29], diamond [30][31][32][33][34][35], and GaNAs [36]. Our results show that room-temperature DNP can be efficiently driven in a material that plays a leading role in the semiconductor industry.We find that SiC color centers can mediate a high degree (>85%) of ESLAC-derived nuclear polarization from at least 5 to 298 K, a surprisingly broad temperature range for this mechanism. 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...

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Dynamic Nuclear Polarization and High-Resolution NMR of Solids

Wind

2007

Encyclopedia of Magnetic Resonance

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High dynamic nuclear polarization at room temperature

Cited by 160 publications

References 11 publications

Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor

Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor

Polarizing Nuclear Spins in Silicon Carbide

Dynamic Nuclear Polarization and High-Resolution NMR of Solids

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