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.
Highlights
Giant magnetoresistance (GMR) denotes a large change in the electrical resistance under the application of a magnetic field and the GMR effect observed in magnetic metallic multilayers (MMM) has become the canonical GMR effect since it transformed the magnetic hard disk storage and memory industries[1,2,3,4,5,6]
The MMM-GMR arises as an applied magnetic field re-aligns the magnetic moments of the successive ferromagnetic layers, which are separated by the nonmagnetic layers[1,2,5,6]
Semiconductor GMR in disordered 2D electronic systems has been a topic of interest from the fundamental physics perspective[11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28], providing insight into weak localization[11,17], weak anti-localization[11,17], electron-electron interaction-induced magnetoresistance[11,14,15,16,18,19,22,23], metal-insulator transitions induced by a magnetic field[29], and GMR in the quantum Hall regime[30,31]
Summary
Giant magnetoresistance (GMR) denotes a large change in the electrical resistance under the application of a magnetic field and the GMR effect observed in magnetic metallic multilayers (MMM) has become the canonical GMR effect since it transformed the magnetic hard disk storage and memory industries[1,2,3,4,5,6]. While previous studies have examined electric field control of magnetoresistance[7,9,10], we show that a supplementary dc-current-bias and associated carrier heating in an ac- and dc- current biased high mobility 2DES provides for a current dependent “non-ohmic” decrease in the conductivity with increasing dc current bias in the absence of a magnetic field, and this effect leads to a dc-current tunable GMR in the presence of 100’s-of-millitesla-type magnetic fields. The negative magnetoresistance observed in the GaAs/AlGaAs system was initially viewed as a manifestation of disorder-induced electron-electron interaction effect[14,15,16] Features such as the concurrent absence of a Hall-effect correction[26], dependence upon scattering type[27], etc., have led to new experimental and theoretical interest. Upon this interest, we report on an effect which is unexpected within the context of previous theory - a current tunable, carrier-heating-induced negative GMR in the GaAs/AlGaAs 2D system
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