Abstract
Nonlinear transport coefficients do not obey, in general, reciprocity relations. We here discuss the magnetic-field asymmetries that arise in thermoelectric and heat transport of mesoscopic systems. Based on a scattering theory of weakly nonlinear transport, we analyze the leading-order symmetry parameters in terms of the screening potential response to either voltage or temperature shifts. We apply our general results to a quantum Hall antidot system. Interestingly, we find that certain symmetry parameters show a dependence on the measurement configuration.
Highlights
We naturally extend our analysis of magnetic-field asymmetries to the nonlinear heat transport coefficients
We show here that a magnetic-field asymmetry arises in the isoelectric case in response to pure thermal gradients due to the asymmetric properties of zα (CP describing the thermal response of U )
In our quantum Hall system, we find that the diagonal elements and are totally independent of (i) the scattering asymmetry factor η and (ii) the electrical asymmetry factor ξ because z1(B) + z1(−B) = z1(B) + z2(B) = De/eDp in equations (B.2a) and (B.4a)
Summary
Are evaluated at equilibrium and are independent of the nonequilibrium screening potential U , while the weakly nonlinear coefficients Gαβγ , Lαβγ , Mαβγ , Rαβγ , Kαβγ and Hαβγ do depend on U in response to the applied electrical and thermal biases. Far [1], the nonlinear electrical conductance Gαβγ in the isothermal case has shown magnetic-field asymmetry since uα (CP describing the voltage response of U ) is not an even function of the magnetic field. In order to quantify the aforementioned magnetic-field asymmetry in the nonlinear transport regime, we define the symmetry ( ) and the asymmetry (A) parameters for G, L,. To leading order in the external fields, the symmetry parameter consists of the symmetric (even) combination between the nonlinear coefficients [G (B) 111 and (− B ) 111 in this case] while the asymmetry parameter A is comprised of the asymmetric (odd) combination, explaining the terminologies. The gate tunability of these parameters, which we demonstrate below for a quantum Hall conductor, can pave the way for controlling the functionality of thermoelectric devices
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