Single-shot measurement of transient nuclear magnetization with spin-noise spectroscopy in n-GaAs microcavities
I. I. Ryzhov, S. V. Poltavtsev, K. V. Kavokin, M. M. Glazov, G. G. Kozlov, M. Vladimirova, D. Scalbert, S. Cronenberger, A. V. Kavokin, A. Lemaître, J. Bloch, V. S. Zapasskii
We exploit spin noise spectroscopy (SNS) to directly observe build-up of dynamic nuclear polarization and relaxation of a perturbed nuclear spin-system to its equilibrium state in a single-shot experiment. The SNS experiments were performed on a layer of bulk $n$-type GaAs embedded into a high-finesse microcavity with negative detuning. The dynamic nuclear spin polarization is observed as a shift of the peak in the electron spin noise spectrum due to the build-up of the Overhauser field acting on the electron spin. The relaxation dynamics of nuclear spin system was revealed in the time-resolved SNS experiments where the exponential decay of the Overhauser field with characteristic timescale of hundreds of seconds was detected. We show that elliptically polarized laser beam tuned in resonance with the cavity mode, whose energy corresponds to nominal transparency of the semiconductor, can nevertheless produce a sizable nuclear polarization.
Digital-Alloy Bragg Mirrors in High-Q Microcavities for Polariton Lasing
St. Petersburg State University（圣彼得堡国立大学）；Spin Optics Laboratory, St. Petersburg State University（圣彼得堡国立大学旋光实验室）；Nanophotonics Research Center, St. Petersburg State University（圣彼得堡国立大学纳米光子学研究中心）；Abrikosov Center for Theoretical Physics, Moscow Center for Advanced Studies（莫斯科高等研究学院阿布里科索夫理论物理中心）；Russian Quantum Center, Skolkovo, Moscow（俄罗斯量子中心）
The selective cooling of $^{75}$As spins by optical pumping followed by adiabatic demagnetization in the rotating frame is realized in a nominally undoped GaAs/(Al,Ga)As quantum well. The rotation of 6 kG strong Overhauser field at the $^{75}$As Larmor frequency of 5.5 MHz is evidenced by the dynamic Hanle effect. Despite the presence of the quadrupole induced nuclear spin splitting, it is shown that the rotating $^{75}$As magnetization is uniquely determined by the spin temperature of coupled spin-spin and quadrupole reservoirs. The dependence of heat capacity of these reservoirs on the exter…
Generation of spin imbalance in nonmagnetic semiconductors is crucial for the functioning of many spintronic devices. An attractive design of spin injectors into semiconductors is based on a spin pumping from a precessing ferromagnet, typically excited by a microwave magnetic field leading to a high power consumption of the device. Here we describe theoretically a spin injector with greatly reduced energy losses, in which the magnetic dynamics is excited by an elastic wave injected into a ferromagnet-semiconductor heterostructure. To demonstrate the efficient functioning of such an injector, w…
Spin transport analysis for a spin pseudovalve-type L_l/SC/L_r trilayer for L = {FeCr, Fe, Co, NiFe, Ni} and SC = {GaSb, InSb, InAs, GaAs, ZnSe}
Instituto de Física La Plata IFLP-CONICET, CCT La Plata. Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata UNLP（拉普拉塔物理研究所 (IFLP-CONICET)、拉普拉塔中央科学技术区、拉普拉塔国立大学理学院）；Grupo de Ciencia y Tecnología de Materiales Cerámicos CYTEMAC, Departamento de Física, Facultad de Ciencias Naturales, Exactas y de la Educación, Universidad del Cauca UNICAUCA（考卡大学自然科学、精确与教育学院物理系陶瓷材料科学与技术小组）
We present a real-time abinitio description of optical orientation in bulk GaAs due to the coupling with an ultrashort circular polarized laser source. The injection of spin polarized electrons in the conduction band is correctly reproduced, and a non vanishing spin polarization ($\mathbf{P}$) parallel to the direction of propagation of the laser ($z$) emerges. A detailed analysis of the generation and the evolution of $\mathbf{P}(t)$ is discussed. The single $\mathbf{k}$-point dynamics is a motion of precession around a fixed axis with constant $|\mathbf{P}|$ and fixed frequency. Instead, the…
Current induced spin-orbit torques (SOTs) in ferromagnet/non-magnetic metal heterostructures open vast possibilities to design spintronic devices to store, process and transmit information in a simple architecture. It is a central task to search for efficient SOT-devices, and to quantify the magnitude as well as the symmetry of current-induced spin-orbit magnetic fields (SOFs). Here, we report a novel approach to determine the SOFs based on magnetization dynamics by means of time-resolved magneto-optic Kerr microscopy. A microwave current in a narrow Fe/GaAs (001) stripe generates an Oersted f…
