Abstract
AbstractLightly doped III–V semiconductor InAs is a dilute metal, which can be pushed beyond its extreme quantum limit upon the application of a modest magnetic field. In this regime, a Mott-Anderson metal–insulator transition, triggered by the magnetic field, leads to a depletion of carrier concentration by more than one order of magnitude. Here, we show that this transition is accompanied by a 200-fold enhancement of the Seebeck coefficient, which becomes as large as 11.3 mV K−1$$\approx 130\frac{{k}_{B}}{e}$$
≈
130
k
B
e
at T = 8 K and B = 29 T. We find that the magnitude of this signal depends on sample dimensions and conclude that it is caused by phonon drag, resulting from a large difference between the scattering time of phonons (which are almost ballistic) and electrons (which are almost localized in the insulating state). Our results reveal a path to distinguish between possible sources of large thermoelectric response in other low-density systems pushed beyond the quantum limit.
Funder
Agence Nationale de la Recherche
Publisher
Springer Science and Business Media LLC
Subject
Condensed Matter Physics,Electronic, Optical and Magnetic Materials
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