Longitudinal spin relaxation of donor-bound electrons in direct band-gap semiconductors

Abstract

We measure the donor-bound electron longitudinal spin-relaxation time (T1) as a function of magnetic field (B) in three high-purity direct-bandgap semiconductors: GaAs, InP, and CdTe, observing a maximum T1 of 1.4 ms, 0.4 ms and 1.2 ms, respectively. In GaAs and InP at low magnetic field, up to ∼2 T, the spin-relaxation mechanism is strongly density and temperature dependent and is attributed to the random precession of the electron spin in hyperfine fields caused by the lattice nuclear spins. In all three semiconductors at high magnetic field, we observe a power-law dependence T1 ∝ B −ν with 3 ν 4. Our theory predicts that the direct spin-phonon interaction is important in all three materials in this regime in contrast to quantum dot structures. In addition, the "admixture" mechanism caused by Dresselhaus spin-orbit coupling combined with single-phonon processes has a comparable contribution in GaAs. We find excellent agreement between high-field theory and experiment for GaAs and CdTe with no free parameters, however a significant discrepancy exists for InP.

Coherence Properties of Shallow Donor Qubits in ZnO

“…The longitudinal spin relaxation time T 1 as a function of the Zeeman energy for donors in GaAs, InP, CdTe and ZnO. The temperature is at 1.5 K. The data for GaAs, InP and CdTe is reproduced from a prior work [22]. The inset shows a typical ZnO optical pumping curve at 5 T and the corresponding laser sequence.…”

“…However, T 1,ZnO is over two orders of magnitude longer as a result of lower spin-orbit coupling. At low field, a positive B-field dependence of T 1 is observed in GaAs and InP due to the short electron correlation time at the donor sites [22]. In ZnO, this mechanism is expected to be weaker because of the small electron Bohr radius.…”

“…However, the indirect band gap of Si makes photon-mediated entanglement and therefore the development of scalable quantum networks challenging [4,16,17]. Studies of donors in direct band-gap III-V materials have shown efficient optical transitions and demonstrated spin control and readout [18][19][20], but their electron spin coherence times are limited by hyperfine interactions with * lpxy1992@uw.edu † kaimeifu@uw.edu the host nuclear spins [21] and spin-orbit coupling [22]. Donors in direct band-gap II-VI semiconductors similarly boast efficient optical transitions [23] and, as we show here in ZnO, can exhibit long coherence times.…”

Universal power law decay of spin polarization in double quantum dot

“…Indeed, according to Refs. 43-48 the spin relaxation caused by the direct spin-phonon coupling [49,50] or spin admixture mechanisms [49,51] should exceed 1 s at magnetic field smaller than 1 T.…”

Quantum Interference Controls the Electron Spin Dynamics in n -GaAs

“…While the mechanisms of electron spin relaxation in semiconductors were largely clarified in theory back in the 1970s [14], for a long time experiments could access the electron spin dynamics only via the Hanle ef- * vasilii.belykh@tu-dortmund.de † glazov@coherent.ioffe.ru fect near zero magnetic field. Since the 1990s more advanced techniques have become available such as pumpprobe methods analyzing the Kerr/Faraday rotation [15,16] or polarization-resolved photoluminescence [17][18][19][20], and elaborated methods like resonant spin amplification [21,22], spin noise spectroscopy [23][24][25] and spin inertia reorientation [26]. Each of these tools has limitations related to the achievable time resolution, the addressable time range or the applicable magnetic field.…”