اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe sign of electron g-factor in GaAs(1-x)N(x) measured by using the Hanle effect
100
0
0.0
(
0
)
تأليف
V.K. Kalevich
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Positive signs of the effective g-factors for free electrons in the conduction band and electrons localized on deep paramagnetic centers have been measured in nitrogen dilute alloy GaAs{0.979}N{0.021} at room temperature. The g-factor signs have been determined from an asymmetry in the depolarization of edge photoluminescence in a transverse magnetic field (Hanle effect) at the oblique incidence of the exciting radiation and oblique-angle detection of the luminescence. The tilted spin polarization of free electrons is induced under interband absorption of circularly polarized light, and the paramagnetic centers acquire spin polarization because of spin-dependent capture of free spin-polarized electrons by these centers. The measured Hanle curve is a superposition of two lines, narrow and broad, with the widths ~400 G and ~50000 G, arising due to the depolarization of localized and free electrons, respectively. The magnitude and direction of the asymmetry in the measured Hanle curve have been found to depend on the partial contributions to the photoluminecsence from the heavy- and light-hole subbands split by a uniaxial deformation of the GaAs{1-x}N{x} film grown on a GaAs substrate. We have extended the theory of optical orientation in order to calculate the excitation spectrum of the photoelectron tilted-spin polarization and the circularly-polarized luminescence spectrum taking into account that, in the strained samples under study, the light-hole subband lies above the heavy-hole one. The results have further been used to calculate the shape of Hanle curve as a function of the excitation and registration energies as well as the incidence and detection angles and to compare the theory with experiment.
قيم البحث
اقرأ أيضاً
Zeeman splitting of 1D hole subbands is investigated in quantum point contacts (QPCs) fabricated on a (311) oriented GaAs-AlGaAs heterostructure. Transport measurements can determine the magnitude of the g-factor, but cannot usually determine the sig
n. Here we use a combination of tilted fields and a unique off-diagonal element in the hole g-tensor to directly detect the sign of g*. We are able to tune not only the magnitude, but also the sign of the g-factor by electrical means, which is of interest for spintronics applications. Furthermore, we show theoretically that the resulting behavior of g* can be explained by the momentum dependence of the spin-orbit interaction.
We determine the effective $g$-factor ($|g^ast|$) of a two-dimensional electron gas (2DEG) using a new method based on capacitance spectroscopy. The capacitance-voltage profile of a 2DEG in an InAs/AlGaSb quantum well measured in an in-plane magnetic
field shows a double-step feature that indicates the Zeeman splitting of the subband edge. The method allows for simultaneous and independent determination of $|g^ast|$ and effective mass $m^ast$. Data suggest that the biaxial tensile strain in the InAs layer has considerable impacts on both $m^ast$ and $g^ast$. Our method provides a means to determine $|g^ast|$ that is complementary to the commonly used coincidence technique.
The electron Lande g factor ($g^{*}$) is investigated both experimentally and theoretically in a series of GaBi$_{x}$As$_{1-x}$/GaAs strained epitaxial layers, for bismuth compositions up to $x = 3.8$%. We measure $g^{*}$ via time-resolved photolumin
escence spectroscopy, which we use to analyze the spin quantum beats in the polarization of the photoluminescence in the presence of an externally applied magnetic field. The experimental measurements are compared directly to atomistic tight-binding calculations on large supercells, which allows us to explicitly account for alloy disorder effects. We demonstrate that the magnitude of $g^{*}$ increases strongly with increasing Bi composition $x$ and, based on the agreement between the theoretical calculations and experimental measurements, elucidate the underlying causes of the observed variation of $g^{*}$. By performing measurements in which the orientation of the applied magnetic field is changed, we further demonstrate that $g^{*}$ is strongly anisotropic. We quantify the observed variation of $g^{*}$ with $x$, and its anisotropy, in terms of a combination of epitaxial strain and Bi-induced hybridization of valence states due to alloy disorder, which strongly perturbs the electronic structure.
We report very efficient spin current generation by the spin Hall effect in the alloy Au0.25Pt0.75, which, as determined by two different direct spin-orbit torque measurements, exhibits a giant internal spin Hall ratio of > 0.58 (anti-damping spin-or
bit torque efficiency of ~ 0.35 in bilayers with Co), a relatively low resistivity of ~ 83 uOhm cm, an exceptionally large spin Hall conductivity of > 7.0x10^5 ohm^-1 m^-1, and a spin diffusion length of 1.7 nm. This work establishes Au0.25Pt0.75 as a milestone spin current generator that provides greater energy efficiency than that yet obtained with other heavy metals or with the topological insulators Bi2Se3 and (Bi,Se)2Te3. Our findings should advance spin-orbit torque-based fundamental research and benefit the development of new fast, efficient spin-orbit torque-driven magnetic memories, skyrmion and chiral domain wall devices, and microwave and terahertz emitters.
The temperature dependence of the electron spin $g$ factor in GaAs is investigated experimentally and theoretically. Experimentally, the $g$ factor was measured using time-resolved Faraday rotation due to Larmor precession of electron spins in the te
mperature range between 4.5 K and 190 K. The experiment shows an almost linear increase of the $g$ value with the temperature. This result is in good agreement with other measurements based on photoluminescence quantum beats and time-resolved Kerr rotation up to room temperature. The experimental data are described theoretically taking into account a diminishing fundamental energy gap in GaAs due to lattice thermal dilatation and nonparabolicity of the conduction band calculated using a five-level kp model. At higher temperatures electrons populate higher Landau levels and the average $g$ factor is obtained from a summation over many levels. A very good description of the experimental data is obtained indicating that the observed increase of the spin $g$ factor with the temperature is predominantly due to bands nonparabolicity.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
