Hyperfine splitting in the electron spin resonance of europium in SnTe

We observed hyperfine splitting of Eu in the highly degenerate semiconductor SnTe. The hyperfine coupling constant A(¹⁵¹Eu) = 29.0 Oe is compared with corresponding values for ¹⁵¹Eu in other host lattices.     

Optically detected electron resonance in phosphorus-doped ZnTe

Samples of ZnTe showing near gap edge luminescence predominantly due to exciton recombination at shallow neutral acceptors and donor- acceptor pair recombination have been investigated using optically detected magnetic resonance (ODMR). Emission polarization changes at 2.318 eV were observed due to magnetic resonance of electrons at g_e = + 0.401 ± 0.004. The observations are consistent with the donor trapped electron resonance resulting from microwave induced changes in donor-acceptor pair photoluminescence.     

Theory of electron spin resonance measurements of chalcogen pairs in Si

Calculations are presented which support the identification of two sulfur-related centers in Si (lying 0.37 and 0.19 eV below the conduction band minima) with (S, S)⁺ and (S, S)⁰ nearest-neighbor substitutional S pairs. Explanations in terms of $\text{meso-bonding}$ are given of the following facts: (i) Although S is much more electronegative than Si, the (S, S)⁺ pair level lies at higher energy than the S⁺ level by ? 0.2 eV; (ii) The hyperfine interaction for (S, S)⁺ is considerably smaller than for the isolated S defect; and (iii) The (S, S)⁺ molecular defect has a hyperfine tensor that is virtually isotropic.     

Single-molecule electron spin resonance

In 1993, two collaborations independently achieved the first optical detection of a single electron spin, using paramagnetic resonance of the triplet state of a single molecule. We review the context of this work and the main later results and give a brief outlook for future experiments based on the detection and manipulation of single spins by optical methods.     

Exchange and dipolar fields in phosphorus-doped silicon measured by electron spin echoes

The instantaneous diffusion effect of Klauder and Anderson has been observed in electron spin echo measurements on phosphorus donors in silicon. Our results give the size and radial dependence of exchange and dipolar interactions between donors. Previous studies of the spin-packet width in this system are re-interpreted.     

Investigating the spectra of electron spin resonance in SiGe/Si heterolayers doped with phosphorous

Studies of the spin resonance spectra of electrons localized on donors and the conduction electrons in Si_{1 ? x} Ge _x layers grown on silicon show that the phosphorous atoms in a SiGe layer can have two positions in the lattice. The line with g ～ 1.998 refers to the electron localized in the phosphorous atom with a predominantly silicon environment; the line with g ～ 1.994 is observed when there is a substantial concentration of germanium in the phosphorous environment.     

Hyperfine-mediated gate-driven electron spin resonance

An all-electrical spin resonance effect in a GaAs few-electron double quantum dot is investigated experimentally and theoretically. The magnetic field dependence and absence of associated Rabi oscillations are consistent with a novel hyperfine mechanism. The resonant frequency is sensitive to the instantaneous hyperfine effective field, and the effect can be used to detect and create sizable nuclear polarizations. A device incorporating a micromagnet exhibits a magnetic field difference between dots, allowing electrons in either dot to be addressed selectively.     

Low temperature electron transport in phosphorus-doped ZnO films grown on Si substrates

Low temperature magneto-transport properties and electron dephasing mechanisms of phosphorus-doped ZnO thin films grown on (1 1 1) Si substrates with Lu₂O₃ buffer layers using pulsed laser deposition were investigated in detail by quantum interference and weak localization theories under magnetic fields up to 10 T. The dephasing length follows the temperature dependence with an index p≈1.6 at higher temperatures indicating electron–electron interaction, yet becomes saturated at lower temperatures. Consistent with photoluminescence measurements and the multi-band simulation of the electron concentration, such behavior was associated with the dislocation densities obtained from x-ray diffraction and mobility fittings, where charged edge dislocations acting as inelastic Coulomb scattering centers were affirmed responsible for electron dephasing. Owing to the temperature independence of the dislocation density, the phosphorus-doped ZnO film maintained a Hall mobility of 4.5 cm² V⁻¹ s⁻¹ at 4 K.     

Mechanisms of flexural-strain-modulated electron spin resonance

Strain-modulated electron spin resonance (SMESR) spectra of V²⁺ and Mn²⁺ centers in MgO are reported and the results are compared with those obtained for MgO : Cr³⁺. The SMESR line intensities show a characteristic angular dependence, proving that modulation of the off-diagonal elements of the $\text{G}$-tensor is the predominant mechanism when a flexural mode of vibration is applied.For V²⁺ a small additional contribution due to modulation of the diagonal elements of $\text{G}$ is present.     

Acoustic detection of electron spin resonance

The ESR-signal of DPPH was recorded by detecting the modulation of the absorbed microwave power with a gas-coupled microphone. This photo-acoustic detection scheme is compared with conventional ESR-detection. Applications of the acoustical detection method to other modulation spectroscopic techniques, particularly NMR, are discussed.     

High resolution electron spin resonance microscopy

NMR microscopy is routinely employed in fields of science such as biology, botany, and materials science to observe magnetic parameters and transport phenomena in small scale structures. Despite extensive efforts, the resolution of this method is limited (>10 microm for short acquisition times), and thus cannot answer many key questions in these fields. We show, through theoretical prediction and initial experiments, that ESR microscopy, although much less developed, can improve upon the resolution limits of NMR, and successfully undertake the 1 mum resolution challenge. Our theoretical predictions demonstrate that existing ESR technology, along with advanced imaging probe design (resonator and gradient coils), using solutions of narrow linewidth radicals (the trityl family), should yield 64 x 64 pixels 2D images (with z slice selection) with a resolution of 1 x 1 x 10 microm at approximately 60 GHz in less than 1h of acquisition. Our initial imaging results, conducted by CW ESR at X-band, support these theoretical predictions and already improve upon the previously reported state-of-the-art for 2D ESR image resolution achieving approximately 10 x 10 mum, in just several minutes of acquisition time. We analyze how future progress, which includes improved resonators, increased frequency of measurement, and advanced pulsed techniques, should achieve the goal of micron resolution.     

Conduction electron spin resonance in magnesium

We report on the observation of conduction electron spin resonance (CESR) in samples of specially purified magnesium. Measurements were made over the temperature range 4.2–300 K and at two frequencies, 9.27 and 21 GHz. It is found that in contrast with previous data, there is no upturn in the low temperature linewidth and little variation between samples.     

Evolution of the 4f electron localization from YbRh2Si2 to YbRh2Pb studied by electron spin resonance

We report on electron spin resonance (ESR) experiments on the Heusler alloy YbRh₂Pb and compare its spin dynamics with that of several other Yb-based intermetallics. A detailed analysis of the derived ESR parameters indicates the extremely weak hybridization, more localized distribution of the 4f states, and a smaller RKKY interaction in YbRh₂Pb. These findings reveal the important interplay between hybridization effects, chemical substitution, and crystalline electric field interactions that determines the ground state properties of strongly correlated electron systems.     

Nature of tunneling electron spin resonance of an isolated surface spin

A phenomenological model has been proposed for tunneling electron spin resonance (ESR) of an isolated surface spin situated in a scanning tunneling microscope (STM), which explains the dependence of features (local maxima) of the tunneling current on the radio-frequency (RF) electric field and on the position of the tip with respect to the spin. A crossover of the line shape of the resonance signals, whose nature in weak and strong pumping fields corresponds to Lorentzian and Fano resonances, respectively, has been interpreted. New ESR–STM effects that are linear and nonlinear in the RF field and are promising for developing the methods of controlling spin qubits have been predicted.     

Clarification of the measurement of surface spin relaxation via conduction electron spin resonance

We clarify the parameterization of the probability of transverse conduction electron spin relaxation. ?, at the surface of a metal. Using Walker's boundary condition on the transverse spin magnetization, we have calculated the ? and thickness dependence of the spin resonance linewidth. The results are discussed in simple physical terms. The recent work of Allam and Vigouroux is shown to contain errors.     

Proton spin structure in the resonance region

We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV相似文献   

Optical detection of electron spin resonance in CdTe

We report the optical detection of electron spin resonance in p-type CdTe at 1.7 K in optical pumping conditions. The Overhauser shift of the electronic resonance, of the order of 45 G, is related to the sign of the electron g-factor g¹. We measure $\text{g}{}^1\text{= -1.59±0.02}$. Using this g¹ value and the previous results on the Knight shift, we deduce the value of the electron wavefunction on Cd in CdTe, which is consistent with the value in CdS.