The B-field range (0.4T, 1.5T) displaying three peaks. Inset: Fourier transform of the shown magnetoresistance, taken Magnetoresistance, with a top gate set to V T G = 0V, and the Figure 1: (a) Shubnikov-de Haas oscillations in the System, and only the total density peak is present in the Fourier spectrum. For magnetic fields above approximately 2 T (not shown) we observe magnetoresistance oscillations related to the total density in the The relation f 1 + f 2 = f t o t, which reflects the fact that the two subband densities sum up to the total density, is reasonably satisfied. An example of such a Fourier transform spectrum obtained from data in the range 0.4 T < B < 1.5 T is shown in the inset of Fig. 1(a). The Fourier transform analysis data in this range results in a spectrum with three peaks corresponding to the populations of each of the two spin-split subbands, and to the Magnetic field is further increased into the region between 0.4 T < B < 2 T, the contribution from the second spin-split subband becomes visible in the oscillations. Subband are observed allowing to extract its density. For very low fields in the interval 0.2 T < B < 0.4 T, only SdH oscillations originating from the higher mobility spin-split Three magnetic field regimes can be identified in the raw data, where SdH oscillations exhibit a different behavior. Observation of the fractional and integer quantum Hall effects,Īs well as by measurements of highly resolved SdH oscillations Grbic04. The high quality of the investigated sample has been demonstrated by the The average mobility in the sample at T = 70mK isġ60’000 cm 2/Vs at a density 3 ×10 11 cm − 2. Ohmic contacts were formed by evaporating Au and Zn and subsequent annealing at 480 oC for 2 min.Īfterwards, a homogeneous Ti/Au topgate was evaporated, whichĪllows to tune the density in the range of 2 − 3 × 10 11 cm − 2. Its width is 100 μm and the separation between adjacent voltage leads is 500 μm. A rectangular Hall bar wasįabricated by standard photolithography. Which is separated from the 2DHG by a 30 nm thick, undopedĪl 0.31Ga 0.69As spacer layer Wieck00. Thick, homogeneously C-doped layer of Al 0.31Ga 0.69As The heterostructureĬonsists of a 5 nm C-doped GaAs cap layer, followed by a 65 nm Results obtained on the sample with the 2DHG formed at the interface 100 nm below the sample surface. We have studied the low-field magnetoresistance in twoĬ-doped p-type GaAs heterostructures with the two-dimensional hole gas (2DHG) buriedĤ5 nm and 100 nm below the surface. Weak perturbation only, as discussed below. Limitations in extracting the spin-orbit scattering time are due to Time of holes and find that it obeys a 1 / T We investigate the temperature dependence of the phase-coherence A phase-coherence time of the holes ofĪround 190 ps, corresponding to a phase-coherence length ofĢ.5 μm is extracted from these measurements. Of intermediate mobilities enables us to simultaneously observeīoth effects and to perform a complementary analysis of spin–orbit interactions in the system.Īnti-localization minimum around B = 0 clearly demonstrates the The fact that our sample is in the regime While for the observation of beating in SdH oscillations higher mobility Typically more pronounced in diffusive, low-mobility samples, Classical magnetoresistance, SdH oscillations,Īnd weak anti-localization in C-doped p-type GaAs
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