Critical collapse of the exchange-enhanced spin splitting in two-dimensional systems
UNSPECIFIED (1998) Critical collapse of the exchange-enhanced spin splitting in two-dimensional systems. PHYSICAL REVIEW B, 58 (19). pp. 13036-13046. ISSN 1098-0121Full text not available from this repository.
The critical filling factor nu(c) where Shubnikov-de Haas oscillations become spin split is investigated for a set of GaAs-GaxAl1-xAs heterojunctions. Finite-temperature magnetoresistance measurements are used to extract the value of nu(c) at zero temperature. The critical point is where the disorder potential has the same magnitude as the exchange energy, leading to the empirical relationship nu(c)=g*n(e)tau(s)h/2m(0). This is valid for all the samples studied, where the density n(e) and single particle lifetime tau(s) both vary by more than an order of magnitude, and g* the exchange-enhanced g factor has a weak dependence on density. For each sample the spin-gap energy shows a linear increase with the magnetic field. Experiments in the tilted magnetic field show the spin gap is the sum of the bare Zeeman energy and an exchange term. This explains why measurements of the enhanced g factor from activation energy studies in the perpendicular field and the coincidence method in tilted fields have previously disagreed. [S0163-1829(98)09343-6].
|Item Type:||Journal Article|
|Subjects:||Q Science > QC Physics|
|Journal or Publication Title:||PHYSICAL REVIEW B|
|Publisher:||AMERICAN PHYSICAL SOC|
|Date:||15 November 1998|
|Number of Pages:||11|
|Page Range:||pp. 13036-13046|
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