Transport in Two-Dimensional Disordered Semimetals

Knap, Michael; Sau, Jay D.; Halperin, Bertrand I.; Demler, Eugene

doi:10.1103/physrevlett.113.186801

Cited by 22 publications

(25 citation statements)

References 31 publications

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“…Away from the neutrality point, the linear field dependence eventually saturates at the strongest (but still classical) fields. Such strong dependence of the magnetoresistance on the carrier density distinguishes the recombination mechanism from the previously proposed extreme quantum [85][86][87] and classical [77][78][79] theories. Magnetoresistance observed in experiments on compensated two-component systems 34,36 does exhibit the essential qualitative features of the recombination mechanism.…”

Section: Discussionmentioning

confidence: 84%

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Magnetoresistance of compensated semimetals in confined geometries

et al. 2017

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Two-component conductors -e.g., semi-metals and narrow band semiconductors -often exhibit unusually strong magnetoresistance in a wide temperature range. Suppression of the Hall voltage near charge neutrality in such systems gives rise to a strong quasiparticle drift in the direction perpendicular to the electric current and magnetic field. This drift is responsible for a strong geometrical increase of resistance even in weak magnetic fields. Combining the Boltzmann kinetic equation with sample electrostatics, we develop a microscopic theory of magnetotransport in two and three spatial dimensions. The compensated Hall effect in confined geometry is always accompanied by electronhole recombination near the sample edges and at large-scale inhomogeneities. As the result, classical edge currents may dominate the resistance in the vicinity of charge compensation. The effect leads to linear magnetoresistance in two dimensions in a broad range of parameters. In three dimensions, the magnetoresistance is normally quadratic in the field, with the linear regime restricted to rectangular samples with magnetic field directed perpendicular to the sample surface. Finally, we discuss the effects of heat flow and temperature inhomogeneities on the magnetoresistance.The theory of magnetotransport in solids 1,2 is a mature branch of condensed matter physics. Measurements of magnetoresistance and classical Hall effect are long recognized as valuable experimental tools to characterize conducting samples. Interpreting the experiments within the standard Drude theory 1,3,4 , one may extract many useful sample characteristics such as the electron mobility and charge density at the Fermi level. However, in materials with more than one type of charge carriers -e.g., semimetals and narrow band semiconductors -the situation is more complex. Indeed, already in 1928 Kapitsa observed unconventional magnetoresistance in semi-metal bismuth films 5 . More recently, interest in magnetotransport has been revived with the discovery of novel twocomponent systems including graphene 6-11 , topological insulators 12-16 , and Weyl semimetals [17][18][19][20][21][22][23][24][25][26][27] . A common feature of all such systems is the existence of the charge neutrality (or, charge compensation) point, where the concentrations of the positively and negatively charged quasiparticles (electron-like and hole-like, respectively) are equal and the system is electrically neutral.A fast growing number of experiments on novel twocomponent materials exhibit unconventional transport properties in magnetic field: (i) linear magnetoresistance (LMR) was reported in graphene and topological insulators close to charge neutrality [85][86][87] . In weak fields, resistivity of two-dimensional (2D) electron systems acquires an interaction correction 88 that is linear in the field.The extreme quantum limit of Refs. 85-87 has been realized in graphene 28 , Bi 2 Te 3 nanosheets 56 , and possibly in the novel topological material LuPdBi 57 . However, this mechanism is applicable...

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Section: Discussionmentioning

confidence: 84%

“…(79) and (81) by taking the appropriate limits. For example, close to charge neutrality, the quantity σ 0 is determined by the equilibrium charge density both in the cases of the electron-hole symmetry and fast Maxwell relaxation (κ → ∞).…”

Section: General Solutionmentioning

confidence: 99%

Magnetoresistance of compensated semimetals in confined geometries

et al. 2017

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“…As a remark, we would like to mention a recent theoretical study of the charge transport in two-dimensional disordered semimetals by Knap et al [40]. In that work it was found that electron and hole puddles, due to smooth fluctuations of the potential, are responsible for a large resistance peak in the CNR measured in HgTe QWs by Olshanetsky et al [41].…”

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confidence: 93%

Anomalously large resistance at the charge neutrality point in a zero-gap InAs/GaSb bilayer

Clericò

Fuentevilla

et al. 2018

New J. Phys.

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We report here our recent electron transport results in spatially separated two-dimensional electron and hole gases with nominally degenerate energy subbands, realized in an InAs(10 nm)/GaSb(5 nm) coupled quantum well. We observe a narrow and intense maximum (∼500 kΩ) in the four-terminal resistivity in the charge neutrality region, separating the electron-like and hole-like regimes, with a strong activated temperature dependence above T=7 K and perfect stability against quantizing magnetic fields. We discuss several mechanisms for that unexpectedly large resistance in this zero-gap semi-metal system including the formation of an excitonic insulator state.

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“…Our theory can be further extended to inhomogeneous samples in the spirit of Ref. [55]. In this case, the result (3) is expected to hold for arbitrary system sizes with W corresponding to the typical size of macroscopic inhomogeneities.…”

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confidence: 99%

Magnetoresistance in Two-Component Systems

et al. 2015

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Two-component systems with equal concentrations of electrons and holes exhibit nonsaturating, linear magnetoresistance in classically strong magnetic fields. The effect is predicted to occur in finite-size samples at charge neutrality due to recombination. The phenomenon originates in the excess quasiparticle density developing near the edges of the sample due to the compensated Hall effect. The size of the boundary region is of the order of the electron-hole recombination length that is inversely proportional to the magnetic field. In narrow samples and at strong enough magnetic fields, the boundary region dominates over the bulk leading to linear magnetoresistance. Our results are relevant for two-and three-dimensional semimetals and narrow band semiconductors including most of the topological insulators.

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Transport in Two-Dimensional Disordered Semimetals

Cited by 22 publications

References 31 publications

Magnetoresistance of compensated semimetals in confined geometries

Magnetoresistance of compensated semimetals in confined geometries

Anomalously large resistance at the charge neutrality point in a zero-gap InAs/GaSb bilayer

Magnetoresistance in Two-Component Systems

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