High-field spin resonance of weakly bound electrons in GaAs

Spin polarization and magnetoluminescence of confined electron-hole systems

“…Experimentally, the dependence of the electron gfactor on well width and magnetic field is well determined 16,17,18,19,20 , and in our case we have:…”

Decoherence and Dephasing in Spin-Based Solid State Quantum Computers

“…Furthermore, T * 2 = 130 ns is obtained at B = 0, which is one order of magnitude larger than the value at B = 1 T. Since the spins are not precessing at B = 0, one could argue that in this particular case T * 2 = T 2 = T 1 = 130 ns, which is the decay of the magnetization in all direction since there is no magnetic field to break the symmetry, hence the increase by one order of magnitude (note that without an external magnetic field, the g factor inhomogeneities discussed in [43,44] will not contribute to T * 2 ). This value of the relaxation time is consistent with the direct ESR measurement of the linewidth to be around 50 MHz in GaAs heterostructure [42].…”

“…We only mention here that in general electron spin relaxation in GaAs is weak due to its relatively weak conduction band spin-orbit coupling-a simple matrix element estimate indicates that the spin relaxation time is of the order of 10-100 ns at low temperatures (T ∼ 4 K), and one should approximately have T 1 ∼ T 2 in high quality GaAs. Such a "long" relaxation time (T 2 ) has recently been directly measured in ESR experiments [42]. We should emphasize that this relaxation time (∼ 10 − 100 ns) is "long" only in a relative sense compared with electron-electron scattering times (∼ fs) or momentum relaxation times (∼ ps)-electron spin relaxation in GaAs should be rather slow due to very weak conduction band spin-orbit coupling, and the observed relaxation times are not long in any absolute sense.…”

“…Coherent manipulation of electron spins and the study of electron spin relaxation have a long history going back to the first ESR experiments half a century ago [36], and ESR remains a key technique to determine electron spin relaxation and study electron spin dynamics [42]. Below we focus on some of the recent experiments that employ alternative optical approaches to study electron spins in semiconductors, especially on optical orientation and related measurements of spin relaxation, which may have particular relevance to solid state quantum computation, where externally controlled optical pulses may be used to coherently manipulate electron spin dynamics in zinc-blende semiconductor structures.…”

Spintronics: Fundamentals and applications

“…There are three important regimes in which the hyperfine interaction leads to spin dephasing of localized electrons: (i) In the limit of small orbital and spin correlation between separated electron states and nuclear spin states, spatial variations in B n lead to inhomogeneous dephasing of the spin ensemble, with the rate proportional to the rms of B n , given by the corresponding thermal or nonequilibrium distribution of the nuclear spins. Such inhomogeneous dephasing is seen by electron-spinresonance (ESR) experiments on donor states both in Si (Feher and Gere, 1959) and in GaAs (Seck et al, 1997). This effect can be removed by spin-echo experiments (in Si donor states performed, for example, by Gordon and Browers, 1958).…”