Tunable electron heating induced giant magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system

Abstract

Electron-heating induced by a tunable, supplementary dc-current (Idc) helps to vary the observed magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system. The magnetoresistance at B = 0.3 T is shown to progressively change from positive to negative with increasing Idc, yielding negative giant-magnetoresistance at the lowest temperature and highest Idc. A two-term Drude model successfully fits the data at all Idc and T. The results indicate that carrier heating modifies a conductivity correction σ1, which undergoes sign reversal from positive to negative with increasing Idc, and this is responsible for the observed crossover from positive- to negative- magnetoresistance, respectively, at the highest B.

Mutual influence between current-induced giant magnetoresistance and radiation-induced magnetoresistance oscillations in the GaAs/AlGaAs 2DES

“…The inset of Fig. 1(b) illustrates the configuration, which is the principal focus of this study, for the transport measurements carried out with a supplementary dc-current, I dc in order to examine the influence of the I dc 80 on both the non-oscillatory- and photo-excited oscillatory magnetoresistance in this system. Thus, the main panel of Fig.…”

“…1(b) exhibits the R xx under constant photo-excitation of f  = 70.1  GHz at P  = 0.77  mW (solid lines) and in the dark (red-dashed-lines) for various values of I dc over the span 0 ≤  I dc  ≤ 20  μA . A detailed study of the influence of I dc on R xx under dark conditions appears elsewhere 80 . Figure 1(b) shows that the non-oscillatory magnetoresistance below B  = 0.05  T is uninfluenced by the I dc while the magnetoresistance for 0.05 ≤  B  ≤ 0.35  T changes from an overall positive magnetoresistance to an overall negative giant magnetoresistance with increasing I dc .…”

Structural and magnetic properties of cobalt doped ZnO thin films deposited by cost effective nebulizer spray pyrolysis technique

“…ZnO posses magnetic properties with influence of cobalt ions (Co), so ZnO:Co DMS can act as a ferromagnetic at room temperature [5]. The transition metal ions like Mn [6], Ni [7] and Co [8] were doped with ZnO thin films and were analyzed via RTFM previously. ZnO systems can be improved by doping cobalt due to its abundant electron-states and high solubility.…”

Study of narrow negative magnetoresistance effect in ultra-high mobility GaAs/AlGaAs 2DES under microwave photo-excitation

“…By now, a number of experimental and theoretical [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] studies have been carried out on the photo-excited transport in low dimensional systems. In addition to the photo-excited effects, the dark magneto-transport properties including positive magnetoresistance 51,52 , giant negative magnetoresistance [53][54][55][56][57][58][59][60][61] , and narrow negative magnetoresistance effect near zero field have also attracted recent experimental attention. So far as the larger negative giant magneto-resistance is concerned, recent studies have shown remarkable features such as size dependence, tunability with supplemental dc-current, and coexistence with-and separability from-radiation induced magnetoresistance oscillations [59][60][61][62][63][64][65] .…”

“…In addition to the photo-excited effects, the dark magneto-transport properties including positive magnetoresistance 51,52 , giant negative magnetoresistance [53][54][55][56][57][58][59][60][61] , and narrow negative magnetoresistance effect near zero field have also attracted recent experimental attention. So far as the larger negative giant magneto-resistance is concerned, recent studies have shown remarkable features such as size dependence, tunability with supplemental dc-current, and coexistence with-and separability from-radiation induced magnetoresistance oscillations [59][60][61][62][63][64][65] . One emerging theory suggests that some of the observed features of the larger negative giant magnetoresistance effect could be a signature of a viscous electron liquid in the low magnetic field quasi ballistic transport regime.…”