DOI: 10.1103/PhysRevB.104.235201
WoS: WOS:000733570400001
Résumé:

The efficiency of the adiabatic demagnetization of the nuclear spin system (NSS) of a solid is limited, if quadrupole effects are present. Nevertheless, despite a considerable quadrupole interaction, recent experiments validated the thermodynamic description of the NSS in GaAs. This suggests that nuclear spin temperature can be used as a probe of nuclear magnetic resonances. We implement this idea by analyzing the modification of the NSS temperature in response to an oscillating magnetic field at various frequencies, an approach termed as the warm-up spectroscopy. It is tested in a n-GaAs sample where both mechanical strain and built-in electric field may contribute to the quadrupole splitting, yielding the parameters of electric field gradient tensors for 75As and both Ga isotopes, 69Ga and 71Ga.

Ref HAL: hal-03447203_v1
Ref Arxiv: 2105.03972
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé:

The efficiency of the adiabatic demagnetization of nuclear spin system (NSS) of a solid is limited, if quadrupole effects are present. Nevertheless, despite a considerable quadrupole interaction, recent experiments validated the thermodynamic description of the NSS in GaAs. This suggests that nuclear spin temperature can be used as the universal indicator of the NSS state in presence of external perturbations. We implement this idea by analyzing the modification of the NSS temperature in response to an oscillating magnetic field at various frequencies, an approach termed as the warm-up spectroscopy. It is tested in a n-GaAs sample where both mechanical strain and built-in electric field may contribute to the quadrupole splitting, yielding the parameters of electric field gradient tensors for 75As and both Ga isotopes, 69Ga and 71Ga.

Commentaires: 12 pages, 9 figures

Ref HAL: hal-03428625_v1
Exporter : BibTex | endNote

Ref HAL: hal-03246864_v1
DOI: 10.1103/PhysRevB.103.205207
WoS: 000655888700004
Exporter : BibTex | endNote
4 Citations
Résumé:

Nuclear magnetism inn-doped semiconductors with a positive hyperfine constant is revisited. Two kindsof nuclear magnetic ordering can be induced by resident electrons in a deeply cooled nuclear spin system.At positive nuclear spin temperature below a critical value, randomly oriented nuclear spin polarons similarto that predicted by Merkulov [Phys. Solid State40, 930 (1998)] should emerge. These polarons are orientedrandomly, and within each polaron, nuclear and electron spins are aligned antiferromagnetically. At negativenuclear spin temperature below a critical value, we predict another type of magnetic ordering—a dynamicallyinduced nuclear ferromagnet. This is a long-range ferromagnetically ordered state involving both electrons andnuclei. It can form if electron spin relaxation is dominated by the hyperfine coupling, rather than by the spin-orbitinteraction. Application of the theory to then-doped GaAs suggests that ferromagnetic order may be reached atexperimentally achievable nuclear spin temperatureN≈−0.5μK and lattice temperatureTL≈5K.

Ref HAL: hal-03246639_v1
DOI: 10.1103/PhysRevB.103.205208
Exporter : BibTex | endNote
Résumé:

Spatiotemporal spin noise spectroscopy is combined with dynamic light scattering in order to reach spatial resolutions down to ∼λ/10. Applied to a system of localized electron spins, an insulating n-doped CdTe layer, this allows us to reveal long spin jump distances ∼ 2.7 μm. Spin noise spectra at large wave vectors q (q 1) provide a snapshot of the spin dynamics before jump (therefore not affected by spin motion), while at smaller q, spin motion sets in. This allows us to unravel the contributions of spin-orbit and hyperfine fields in the electron spin relaxation and to determine self-consistently all parameters relevant to the spin dynamics. We propose a phenomenological equation inspired by studies of atomic jump diffusion by neutron scattering, which includes the relevant spin relaxation mechanisms and the effect of time of flight of the spin fluctuation across the laser spot. This modeling reproduces all experimental results.