Size-dependent giant-magnetoresistance in millimeter scale GaAs/AlGaAs 2D electron devices

Abstract

Large changes in the electrical resistance induced by the application of a small magnetic field are potentially useful for device-applications. Such Giant Magneto-Resistance (GMR) effects also provide new insights into the physical phenomena involved in the associated electronic transport. This study examines a “bell-shape” negative GMR that grows in magnitude with decreasing temperatures in mm-wide devices fabricated from the high-mobility GaAs/AlGaAs 2-Dimensional Electron System (2DES). Experiments show that the span of this magnetoresistance on the magnetic-field-axis increases with decreasing device width, W, while there is no concurrent Hall resistance, Rxy, correction. A multi-conduction model, including negative diagonal-conductivity, and non-vanishing off-diagonal conductivity, reproduces experimental observations. The results suggest that a size effect in the mm-wide 2DES with mm-scale electron mean-free-paths is responsible for the observed “non-ohmic” size-dependent negative GMR.

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

“…As a consequence, the study of potential new mechanisms for realizing GMR in semiconductors has been a useful line of basic research78910. Semiconductor GMR in disordered 2D electronic systems has also been a topic of interest from the fundamental physics perspective111213141516171819202122232425262728, providing insight into weak localization1117, weak anti-localization1117, electron-electron interaction-induced magnetoresistance1114151618192223, metal-insulator transitions induced by a magnetic field29, and GMR in the quantum Hall regime3031.…”

“…The ultra high mobility GaAs/AlGaAs system has been the subject of intense magnetotransport studies at high filling factors or low magnetic fields because improvements in material quality in this 2D electron system have led to a steady stream of spectacular new phenomena such as the microwave radiation-induced zero-resistance states and associated magnetoresistance oscillations3233343536373839404142434445464748495051525354555657585960616263646566676869707172, magnetoresistance that depends on the electron-electron interactions1415161823, device size192126, scatterer type20222427, temperature, carrier density24, and orientation of magnetic field25, giant resonances at the second harmonic of cyclotron resonance737475, etc. The negative magnetoresistance observed in the GaAs/AlGaAs system was initially viewed as a manifestation of disorder-induced electron-electron interaction effect141516.…”

Evidence of radiation-driven Landau states in 2D electron systems: Magnetoresistance oscillations phase shift

“…Both effects were totally unexpected when they were first obtained revealing some type of new radiation-matter interaction or coupling assisting electron magnetotransport [3][4][5]. Despite that over the last few years important experimental [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and theoretical efforts [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] have been made on MIRO and ZRS, their physical origin still remains controversial and far from reaching a definite consensus among the people devoted to this field. For instance, the two, in principle, accepted theoretical models explaining MIRO, (displacement [31] and inelastic [35] models) are under question in regards of recent (and even older) experimental results [43,44] that they are not able to explain.…”

Combined study of microwave-power/linear-polarization dependence of the microwave-radiation-induced magnetoresistance oscillations in GaAs/AlGaAs devices

“…However, there still remain two issues that remain unsettled: the power dependence of the amplitude of the microwave radiation-induced magnetoresistance oscillations and the linear polarization sensitivity of these same oscillations. The experimental [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and theoretical [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] status of these aspects are as follows: For the power dependence, some experimental results [14] have indicated that MRiMOs amplitude increase non-linearly with the microwave power, as the radiation driven electron orbit model [33] has theoretically confirmed a non-linear power relation. In contrast, the inelastic model [27] suggests that the amplitude of the radiation-induced magnetoresistance oscillations should increase linearly with the microwave power, as suggested in early experimental work [ [2].…”