Anomalous High-Temperature Magnetoresistance in a Dilute 2D Hole System

Area of Science:

• Condensed Matter Physics
• Quantum Wells
• Semiconductor Heterostructures

Background:

• Dilute two-dimensional (2D) hole systems in GaAs/AlGaAs quantum wells are studied.
• High ratio of Coulomb energy to Fermi energy (r_s = 20-30) indicates strong carrier interactions.

Purpose of the Study:

• To investigate the unusual temperature-dependent magnetoresistance in a dilute 2D hole system.
• To understand the underlying transport mechanisms in the strongly interacting regime (r_s >> 1).

Main Methods:

• Experimental measurements of magnetoresistance in GaAs/AlGaAs quantum wells.
• Analysis of transport properties at varying temperatures (up to T ~ E_F) and magnetic fields.
• Theoretical interpretation based on Fermi liquid and hydrodynamic transport models.

Main Results:

• A negative parabolic magnetoresistance characteristic of Fermi liquid behavior observed at low temperatures (< 0.4 K).
• An unexpected positive magnetoresistance emerges at higher temperatures, increasing with temperature.
• This high-temperature positive magnetoresistance is attributed to viscous transport in the hydrodynamic regime.

Conclusions:

• Strongly interacting carriers in 2D systems exhibit complex magnetoresistance behavior.
• Viscous transport and hydrodynamic effects become significant at higher temperatures in the r_s >> 1 regime.
• Findings offer insights into collective carrier transport and potential for novel magnetoresistance applications.