Theory of Spin Noise in Nanowires (original) (raw)
Related papers
Two-beam spin noise spectroscopy
Applied Physics Letters, 2013
We propose a method of two-beam spin noise spectroscopy to test the spin transport at equilibrium via analysis of correlations between time-shifted spin fluctuations at different space locations. This method allows one to determine the strength of spin-orbit interaction and spin relaxation time and separate spin noise of conducting electrons from the background noise of localized electrons. We formulate a theory of two-beam spin noise spectroscopy in semiconductor wires with Bychkov-Rashba spin-orbit interaction taking into account several possible spin relaxation channels and finite size of laser beams. Our theory predicts a peak shift with respect to the Larmor frequency to higher or lower frequencies depending on the strength of spin orbit interaction and distance between the beams. The two-beam spin noise spectroscopy could find applications in experimental studies of semiconductors, emergent materials and many other systems.
2003 Third IEEE Conference on Nanotechnology, 2003. IEEE-NANO 2003., 2003
We study high-field spin transport of electrons in a quasi one-dimensional channel of a GaAs gate controlled spin interferometer (SPINFET) using a semiclassical formalism (spin density matrix evolution coupled with Boltzmann transport equation). Spin dephasing (or depolarization) is predominantly caused by D'yakonov-Perel' relaxation associated with momentum dependent spin orbit coupling effects that arise due to bulk inversion asymmetry (Dresselhaus spin orbit coupling) and structural inversion asymmetry (Rashba spin orbit coupling). Spin dephasing length in a one dimensional channel has been found to be an order of magnitude higher than that in a two dimensional channel. This study confirms that the ideal configuration for a SPINFET is one where the ferromagnetic source and drain contacts are magnetized along the axis of the channel. The spin dephasing length in this case is about 22.5µm at lattice temperature of 30K and 10µm at lattice temperature of 77K for an electric field of 2kV/cm. Spin dephasing length has been found to be weakly dependent on the driving electric field and strongly dependent on the lattice temperature.
Spin noise explores local magnetic fields in a semiconductor
Scientific reports, 2016
Rapid development of spin noise spectroscopy of the last decade has led to a number of remarkable achievements in the fields of both magnetic resonance and optical spectroscopy. In this report, we demonstrate a new - magnetometric - potential of the spin noise spectroscopy and use it to study magnetic fields acting upon electron spin-system of an n-GaAs layer in a high-Q microcavity probed by elliptically polarized light. Along with the external magnetic field, applied to the sample, the spin noise spectrum revealed the Overhauser field created by optically oriented nuclei and an additional, previously unobserved, field arising in the presence of circularly polarized light. This "optical field" is directed along the light propagation axis, with its sign determined by sign of the light helicity. We show that this field results from the optical Stark effect in the field of the elliptically polarized light. This conclusion is supported by theoretical estimates.
Nanoscale, 2015
Spintronic devices are of fundamental interest for their nonvolatility and great potential for low-power electronics applications. The implementation of those devices usually favors materials with long spin lifetime and spin diffusion length. Recent spin transport studies on semiconductor nanowires have shown much longer spin lifetimes and spin diffusion lengths than those reported in bulk/thin films. In this paper, we have reviewed recent progress in the electrical spin injection and transport in semiconductor nanowires and drawn a comparison with that in bulk/thin films. In particular, the challenges and methods of making high-quality ferromagnetic tunneling and Schottky contacts on semiconductor nanowires as well as thin films are discussed. Besides, commonly used methods for characterizing spin transport have been introduced, and their applicability in nanowire devices are discussed. Moreover, the effect of spin-orbit interaction strength and dimensionality on the spin relaxation and hence the spin lifetime are investigated.
Spin Fluctuations and "Spin Noise
Clusters and Nano-Assemblies - Physical and Biological Systems, 2005
We have theoretically studied the temporal fluctuations and the resulting kinetic noise in the average spin polarization of an electron ensemble drifting in a quantum wire under a high electric field. Electrons are initially injected in the wire from a ferromagnetic contact with all their spins polarized along the wire axis. The average spin polarization of the ensemble decays during transport because of D'yakonov-Perel' relaxation caused by both Rashba and Dresselhaus interactions. Once steady state is reached, the average spin fluctuates randomly around zero. The time average of this fluctuation is zero. The autocorrelation function of this fluctuation approximates a Lorentzian and so does the spectral density. To our knowledge, this is the first study of spin fluctuations and "spin noise" in a nanostructure.
Spin-Valley Coupling Anisotropy and Noise in CMOS Quantum Dots
Physical Review Applied, 2022
One of the main advantages of silicon spin qubits over other solid-state qubits is their inherent scalability and compatibility with the 300 mm CMOS fabrication technology that is already widely used in the semiconductor industry, whilst maintaining high readout and gate fidelities. We demonstrate detection of a single electron spin using energy-selective readout in a CMOS-fabricated nanowire device with an integrated charge detector. We measure a valley splitting of 0.3 meV and 0.16 meV in two similar devices. The anisotropy of the spin-valley mixing is measured and shown to follow the dependence expected from the symmetry of the local confinement, indicating low disorder in the region of the quantum dot. Finally the charge noise in the spin-valley coupling regime is investigated and found to induce fluctuations in the qubit energy in the range of 0.6 GHz/ √ Hz.
Spatiotemporal Spin Noise Spectroscopy
Physical Review Letters, 2019
We report on the potential of a new spin noise spectroscopy approach by demonstrating all-optical probing of spatiotemporal spin fluctuations. This is achieved by homodyne mixing of a spatially phasemodulated local oscillator with spin-flip scattered light, from which the frequency and wave vector dependence of the spin noise power is unveiled. As a first application of the method we measure the spatiotemporal spin noise in weakly n-doped CdTe layers, from which the electron spin diffusion constant and spin relaxation rates are determined. The absence of spatial spin correlations is also shown for this particular system.
Electronic noise in magnetic low-dimensional materials and nanostructures
Journal of Magnetism and Magnetic Materials, 2003
After a brief review underlining the power of electronic noise studies to probe local magnetic instabilities, we present new data in three different systems in terms of dimensionality and magnetic ordering: the first results we present deal with low-frequency longitudinal and Hall resistance fluctuations in Ni nanostructures, where we address the questions of the inhomogeneous behavior of the noise at a nanometric scale. In order to get some insight into the atomic process, we report on noise generated in atomic contacts of Ni obtained by the break junction technique. And finally, we present the first electronic noise study in a one-dimensional frustrated magnetic Ca 3 Co 2 O 6 single crystal composed of parallel Co spin chains. From the magnetic noise analysis, we discuss the interplay between the low-temperature threedimensional magnetic ordering and the spin-dependent hopping conductivity on the Co sites.
LIMITATIONS OF DRIFT-DIFFUSION MODEL FOR STUDYING SPIN TRANSPORT IN NANOWIRES
We study spin relaxation of upstream electrons in a multi subband quantum wire due to D'yakonov-Perel' mechanism. Our study reveals that upstream spin relaxation is non-monotonic in space and has a complex dependence on electron distributions over various subbands. Classical drift-diffusion model of spin transport fails to account for these features and hence this is inappropriate for studying spin transport in quantum wires.
Ultralong spin lifetimes in one-dimensional semiconductor nanowires
Applied Physics Letters, 2019
We experimentally demonstrate ultralong spin lifetimes of electrons in the one-dimensional (1D) quantum limit of semiconductor nanowires. Optical probing of single wires of different diameters reveals an increase in the spin relaxation time by orders of magnitude as the electrons become increasingly confined until only a single 1D sub-band is populated after thermalization. We find the observed spin lifetimes of more than 200 ns to result from the robustness of 1D electrons against major spin relaxation mechanisms, highlighting the promising potential of these wires for long-range transport of coherent spin information.