[Paper Review] Effect of the In-Plane Magnetic Field on Conduction of the Si-inversion Layer: Magnetic Field Driven Disorder

V. M. Pudalov, G. Brunthaler+2 more|arXiv (Cornell University)|Mar 4, 2001

Surface and Thin Film Phenomena2 references3 citations

TL;DR

This paper demonstrates that in-plane magnetic fields in Si inversion layers induce a disorder-like effect, suppressing metallic-like resistivity behavior by increasing scattering rates. The field continuously suppresses the resistivity drop with temperature, mimicking increased disorder or temperature, and restores high-temperature resistivity without activation, constraining theoretical models to include field-dependent disorder mechanisms.

ABSTRACT

We compare the effects of temperature, disorder and parallel magnetic field on the metallic-like temperature dependence of the resistivity. We found a similarity between the effects of disorder and parallel field: the parallel field weakens the metallic-like conduction in high mobility samples and make it similar to that for low-mobility samples. We found a smooth continuous effect of the in-plane field on conduction, without any threshold. While conduction remains non-activated, the parallel magnetic field restores the same resistivity value as the high temperature does. This matching sets substantial constraints on the choice of the theoretical models developed to explain the mechanism of the metallic conduction and parallel field magnetoresistance in 2D carrier systems. We demonstrate that the data for magneto- and temperature dependence of the resistivity of Si-MOS samples in parallel field may be well described by a simple model of the magnetic field dependent disorder.

Motivation & Objective

• To investigate the effect of in-plane magnetic fields on resistivity in high-mobility Si-MOS 2D systems.
• To determine whether the magnetic field's influence on conduction resembles that of disorder or temperature.
• To constrain theoretical models of metallic conduction and parallel-field magnetoresistance in 2D systems.
• To examine the continuity and threshold behavior of the magnetic field's effect on resistivity.
• To test whether the resistivity recovery at high temperatures under magnetic field supports a field-dependent disorder mechanism.

Proposed method

• Measured temperature and in-plane magnetic field dependence of resistivity in multiple Si-MOS samples with varying mobilities.
• Compared resistivity behavior across samples with peak mobilities spanning a factor of 25 to isolate mobility effects.
• Used a phenomenological model with field-dependent scattering rate (ρ₀(B)) and temperature-dependent resistivity drop (ρ₁(T)) to fit data.
• Fitted data using Eq. (2) with parameters ρ₀(B), ρ₁, and Δ to describe the resistivity as a function of temperature and magnetic field.
• Analyzed the critical carrier density n_c(B) and its evolution under magnetic field to map the metal-insulator transition.
• Evaluated the role of spin and orbital effects via comparison with existing Shubnikov-de Haas and Hall data.

Experimental results

Research questions

• RQ1 Does the in-plane magnetic field suppress metallic-like resistivity in a manner analogous to increasing disorder or temperature?
• RQ2 Is the effect of the in-plane magnetic field on resistivity continuous, without a threshold or abrupt transition?
• RQ3 Can the combined temperature and magnetic field dependence of resistivity be described by a single mechanism of field-dependent disorder?
• RQ4 Does the recovery of high-temperature resistivity under magnetic field imply a non-activated transport mechanism?
• RQ5 What is the role of spin subbands and inter-subband scattering in the observed magnetoresistance?

Key findings

• The in-plane magnetic field suppresses the metallic-like resistivity drop in high-mobility Si-MOS samples, making their conduction resemble that of low-mobility samples.
• The effect of the magnetic field on resistivity is smooth and continuous, with no threshold, indicating a gradual increase in scattering rate.
• At high temperatures, the resistivity under in-plane magnetic field recovers to the same value as the high-temperature 'Drude' resistivity, even though transport remains non-activated.
• The magnetoresistance and temperature dependence of resistivity can be quantitatively described by a model of magnetic field-dependent disorder, with increasing T-independent scattering rate ρ₀(B).
• The critical carrier density n_c increases with in-plane magnetic field, consistent with enhanced disorder, and the resistivity drop magnitude (ρ₁+ρ₀)/ρ₀ decreases with field.
• The model with field-dependent disorder fits the data well, particularly when using a power-law factor T⁻ᵖ instead of a polynomial to model the 'tilted separatrix' in the resistivity transition.