Giant Seebeck effect across the field-induced metal-insulator transition of InAs

Abstract

Lightly 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 two-hundred-fold enhancement of the Seebeck coefficient which becomes as large as 11.3mV.K −1 ≈ 130 k B e at T = 8K and B = 29T. 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.

Large enhancement of thermopower at low magnetic field in compensated semimetals

“…These experimental results suggest that there is a mech- anism for enhancement of the thermopower by magnetic field that is specific to compensated semimetals and does not require the extreme quantum limit. Throughout this paper we neglect the effects of phonon drag, which generally serve to increase the thermopower [22][23][24].…”

Wide Critical Fluctuations of the Field-Induced Phase Transition in Graphite

“…Future studies of the specific heat at higher magnetic field would shed light to the BCS-BEC crossover as one approaches the maximum transition temperature around 47T, where the degeneracy temperature and critical temperature become close to each other [29]. Specific heat studies on other dilutes metals pushed to extreme quantum limit and hosting field-induced state (such as bismuth [31,32], InAs [33], TaAs [34] or ZrTe 5 [35]) could bring interesting insights.…”