Anomalous Hall effect of metallicBe∕Sipairδ-doped GaAs structures

Abstract

Metallic samples of Be and Si pair ␦-doped GaAs structures which undergo a metal-insulator transition with a decrease in the hole concentration are investigated by Hall resistance and magnetoresistance measurements. The anomalous Hall effect and negative magnetoresistance are observed from the samples in a temperature range above 70 K. Magnitudes of negative magnetoresistance and anomalous Hall resistance significantly vary among the samples, although their doping conditions are close to one another. Dependence of anomalous Hall resistance on the temperature and applied magnetic field is closely correlated to that of negative magnetoresistance for each sample. Their dependence is explained on the basis of a paramagnetic state of localized magnetic moments coexisting with itinerant holes in these samples. Both anomalous Hall effect and negative magnetoresistance decrease with lowering the temperature from 150 K and vanish at a temperature around 70 K, a possible origin of which is discussed.

Large anomalous Hall resistance of pair δ-doped GaAs structures grown by molecular-beam epitaxy

“…The nonlinearity of the Hall voltage for sample 5 is significantly greater than that for other samples grown under higher As fluxes. 3 Figure 3͑b͒ shows the longitudinal resistance of sample 5 as a function of the applied magnetic field B. The magnetic field was applied in the direction parallel to the current.…”

“…By utilizing these techniques, different approaches can be used for incorporating the spin degree of freedom into semiconductors. In a recent study, 3 we observed a Hall resistance which has a nonlinear dependence on the applied magnetic field from Be/ Si pair ␦-doped GaAs structures grown by molecular-beam epitaxy ͑MBE͒. In the pair ␦-doped GaAs structures which exhibit p-type conduction, a metalinsulator transition occurs as a result of the strong localization of holes in the ␦-doped layers.…”

“…4 With the applied magnetic field whose direction is parallel to the current, negative magnetoresistance was observed from these structures in the temperature range where the nonlinear Hall resistance occurs. 3,5 Because of the strong correlation of the occurrence of the negative magnetoresistance and the nonlinear Hall resistance, the observed Hall resistance was explained as an anomalous Hall effect ͑AHE͒ by assuming the existence of localized spins in the structures. The possibility of the existence of localized spins in the pair ␦-doped structures was suggested from their similarity to localized spins associated with impurity states in bulk semiconductors such as P doped Si.…”

Possible anomalous Hall effect of Be/Si pair delta‐doped GaAs structures

“…One is the structure similar to those used in our pervious studies [6], in while a buffer layer was grown under different As fluxes to different thicknesses at 580 ℃ as shown in Fig. 1(a).…”

“…We also found that the samples exhibiting negative magnetoresistance gave rise to the Hall resistance which has nonlinear dependence on the applied magnetic field. Because of their close correlation, the nonlinear Hall resistance and negative magnetoresistance were explained as a result of localized spins in delta-doped layers [6]; they are explained as the anomalous Hall effect(AHE) and reduced spin-disorder scattering, respectively.…”