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Charge and Entropy Transport in Dilute Metals

Abstract : This manuscript focuses on the electronic heat/charge transport dichotomy and the beyond-quantum-limit transport properties of dilute metals. In the first part, we report on a study of two semi-metals, WP2 and Sb. In both cases, we found that the Wiedemann-Franz (WF) law is recovered at low temperature (T ≈ 2 K), but not at T ≈ 15 K. We show that the finite-temperature deviation from the WF law is due to a mismatch between the prefactors of the T 2-resistivities. In the Boltzmann picture of transport, this difference is associated with abundant small-angle scattering among electrons. However, we argue that momentum-conserving fermionic collisions in normal-state liquid 3He also produce a thermal T2-resistivity. This opens the door for an alternative interpretation : the existence of a hydrodynamic regime of electrons in these semi-metals. In this scenario, the larger T2 thermal resistivity is due to momentum-conserving electronic collisions. In the case of Sb, the ratio of the two T2-prefactors evolves with sample size. This observation supports the hydrodynamic scenario. Finally, we find a large hydrodynamic correction in the phononic thermal conductivity. The second part deals with the fate of the Fermi sea in the quantum limit (QL). In the doped semi-conductor InAs, we observe a field-induced insulating state for all geometries of transport. This field-induced state is accompanied by a ‘giant’ Seebeck effect. The comparison with the succession of field-induced states in graphite up to B = 90 T reveals that the ground state of a 3D electron gas beyond the QL is system-dependent. The observation of a saturating resistivity accompanied by vanishing thermoelectric coefficients in InAs points to the existence of a conductive surface state.
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Contributor : Alexandre Jaoui <>
Submitted on : Monday, September 28, 2020 - 9:24:16 AM
Last modification on : Thursday, October 15, 2020 - 4:06:25 AM


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  • HAL Id : tel-02950527, version 1


Alexandre Jaoui. Charge and Entropy Transport in Dilute Metals. Strongly Correlated Electrons [cond-mat.str-el]. Sorbonne Université, 2019. English. ⟨NNT : 2019SORUS151⟩. ⟨tel-02950527⟩



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