Direct measurement of the spin gaps in a gated GaAs two-dimensional electron gas

Chi-Te Liang,Gil-Ho Kim,Yang Fang Chen,David A Ritchie,Tsai-Yu Huang,Michelle Y Simmons

doi:10.1186/1556-276x-8-138

Chi-Te Liang, Gil-Ho Kim + Show 4 more

Open Access

https://doi.org/10.1186/1556-276x-8-138

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Abstract

We have performed magnetotransport measurements on gated GaAs two-dimensional electron gases in which electrons are confined in a layer of the nanoscale. From the slopes of a pair of spin-split Landau levels (LLs) in the energy-magnetic field plane, we can perform direct measurements of the spin gap for different LLs. The measured g-factor g is greatly enhanced over its bulk value in GaAs (0.44) due to electron–electron (e-e) interactions. Our results suggest that both the spin gap and g determined from conventional activation energy studies can be very different from those obtained by direct measurements.

Highlights

With the growing interest in spin-based quantum computation and spintronic applications [1], there is an increasing need to understand and accurately determine critical parameters of the electron spin degree of freedom
Our results provide direct experimental evidence that both the spin gap and g-factor determined from the direct measurements are very different from those obtained by the conventional activation energy studies
We suggest that the determined g* is in the zero disorder limit since the positions of the spin-split Landau levels are located using Equation 2

Summary

Introduction

With the growing interest in spin-based quantum computation and spintronic applications [1], there is an increasing need to understand and accurately determine critical parameters of the electron spin degree of freedom. It is well established that when measuring an electron spin in an external magnetic field B, it can either align parallel to or antiparallel to B. The energy difference between these two discrete states, known as the spin gap or Zeeman splitting, is given by gμBB where g is the Lande g-factor and μB is the Bohr magneton. It is worth mentioning that successful application of the wide range of possible spindependent phenomena requires effective techniques for the electrical injection of spin-polarized currents [2]. It is highly desirable that the generation of the spin currents can be accomplished without requiring the use of extremely high B. An accurate measurement of the spin gap and g-factor would

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Conclusion