Anomalous Conductance Oscillations in the Hybridization Gap of 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>InAs</mml:mi><mml:mo>/</mml:mo><mml:mi>GaSb</mml:mi></mml:mrow></mml:math>
 Quantum Wells

Han, Ziyao; Li, Tingxin; Zhang, Long; Sullivan, Gerard; Du, Rui-Rui

doi:10.1103/physrevlett.123.126803

Cited by 28 publications

(30 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimentally, evidence for QOs in insulators was reported only very recently in topological Kondo insulators under high magnetic fields 6,7 and InAs/GaSb quantum wells 25,26 . In contrast to our experiment, either no evidence for high mobility was extracted 6,7,25 or the sample remained conducting 26 (i.e., resistance ~ h/e 2 ) in these previous experiments.…”

Section: Quantum Oscillations In the Insulatormentioning

confidence: 99%

Landau quantization and highly mobile fermions in an insulator

Wang

Guo

Jia

et al. 2021

Nature

View full text Add to dashboard Cite

In strongly correlated materials, quasiparticle excitations can carry fractional quantum numbers. An intriguing possibility is the formation of fractionalized, chargeneutral fermions, e.g., spinons 1 and fermionic excitons 2,3 , that result in neutral Fermi surfaces and Landau quantization 4,5 in an insulator. While previous experiments in quantum spin liquids 1 , topological Kondo insulators [6][7][8] , and quantum Hall systems 3,9 have hinted at charge-neutral Fermi surfaces, evidence for their existence remains far from conclusive. Here we report experimental observation of Landau quantization in a two dimensional (2D) insulator, i.e., monolayer tungsten ditelluride (WTe2), a large gap topological insulator [10][11][12][13] . Using a detection scheme that avoids edge contributions, we uncover strikingly large quantum oscillations in the monolayer insulator's magnetoresistance, with an onset field as small as ~ 0.5 tesla. Despite the huge resistance, the oscillation profile, which exhibits many periods, mimics the Shubnikov-de Haas oscillations in metals. Remarkably, at ultralow temperatures the observed oscillations evolve into discrete peaks near 1.6 tesla, above which the Landau quantized regime is fully developed. Such a low onset field of quantization is comparable to high-mobility conventional two-dimensional electron gases. Our experiments call for further investigation of the highly unusual ground state of the WTe2 monolayer. This includes the influence of device components and the possible existence of mobile fermions and charge-neutral Fermi surfaces inside its insulating gap. MainBulk tungsten ditelluride (WTe2) is a compensated semimetal in which an equal number of electrons and holes co-exist 14 . The semimetallic behavior remains when the material is thinned down to the trilayers 11,15 . In bilayers and monolayers, nevertheless, an insulating gap is observed 11 , giving rise to the high-temperature quantum spin Hall effect in monolayers [10][11][12][13] . However, the mechanism for the gap opening remains mysterious 10,11,16,17 . The observation of superconductivity when the monolayer is doped with a low electron density 18,19 highlights the unusual nature of the insulating state.

show abstract

Section: Quantum Oscillations In the Insulatormentioning

confidence: 99%

Landau quantization and highly mobile fermions in an insulator

Wang

Guo

Jia

et al. 2021

Nature

View full text Add to dashboard Cite

show abstract

“…At temperatures sufficiently higher than the activation gap, there are essentially two peaks corresponding to the unhybridized conduction and f -electrons, and these peaks develop to form the anomalous peaks at low temperature via the Kondo effect. Our results are qualitatively applicable not only to Kondo insulators but also to other band inverted insulators such as a quantum well [44][45][46] .…”

Section: Discussionmentioning

confidence: 58%

“…At the same time, signal amplitudes would be reduced at low temperature, which is a common subtle issue also for observables where only states near the chemical potential contribute 17,44 . Nevertheless, quantum oscillations in static longitudinal transport have indeed been observed not only in YbB 12 but also in band inverted insulating quantum wells at low temperature 4,45,46 , and discussed theoretically 21 . Since cyclotron resonance can be observed at relatively high temperature in general, anomalous cyclotron resonance can be used in some temperature range and provide a useful insight for the observed quantum oscillations.…”

Section: Cyclotron Resonancementioning

confidence: 92%

Cyclotron resonance in Kondo insulator

Tada

2020

Preprint

View full text Add to dashboard Cite

Motivated by the recent experimental observations of quantum oscillations in the Kondo insulators SmB6 and YbB12, we study magneto-optical conductivity of Kondo insulators. We show that there exist non-trivial cyclotron resonance peaks in a frequency domain below the hybridization gap as a result of the characteristic Landau level structure of the system. Furthermore, these low energy peaks are enhanced near the insulator-metal phase transition driven by an applied magnetic field and stable even at low temperatures. They are smoothly connected via Kondo effect to resonance peaks for unhybridized conduction and f -electrons at high temperature. The non-trivial cyclotron resonance is a dynamical counterpart of quantum oscillations in static quantities, and through this intimate connection it will provide a useful insight for the latter.

show abstract

“…YbB 12 [8,9], and motivated theoretical works [10][11][12][13][14][15][16] which unearthed scenarios beyond the LK paradigm. For example, inverted band insulators could lead to such anomalous QO with a non-LK temperature evolution [10], which were then predicted [17] and subsequently observed in quantum well heterostructures [18,19]. Alternatively, it was shown that charge neutral fermions from fractionalization in strongly correlated insulators can potentially give rise to QOs via indirectly coupling to the orbital magnetic field [14,15].…”

mentioning

confidence: 92%

Anomalous Quantum Oscillations in a Heterostructure of Graphene on a Proximate Quantum Spin Liquid

Leeb,

Polyudov,

Mashhadi

et al. 2020

Preprint

View full text Add to dashboard Cite

The quasi two-dimensional Mott insulator α−RuCl3 is proximate to the sought-after Kitaev quantum spin liquid (QSL). In a layer of α−RuCl3 on graphene the dominant Kitaev exchange is further enhanced by strain. Recently, quantum oscillation (QO) measurements of such α−RuCl3 / graphene heterostructures showed an anomalous temperature dependence beyond the standard Lifshitz-Kosevich description. Here, we develop a theory of anomalous QO in an effective Kitaev-Kondo lattice model in which the itinerant electrons of the graphene layer interact with the correlated magnetic layer via spin interactions. At low temperatures a heavy Fermi liquid emerges such that the neutral Majorana fermion excitations of the Kitaev QSL acquire charge by hybridising with the graphene Dirac band. Using ab-initio calculations to determine the parameters of our low energy model we provide a microscopic theory of anomalous QOs with a non-LK temperature dependence consistent with our measurements. We show how remnants of fractionalized spin excitations can give rise to characteristic signatures in QO experiments.

show abstract

Anomalous Conductance Oscillations in the Hybridization Gap of InAs/GaSb Quantum Wells

Cited by 28 publications

References 39 publications

Landau quantization and highly mobile fermions in an insulator

Landau quantization and highly mobile fermions in an insulator

Cyclotron resonance in Kondo insulator

Anomalous Quantum Oscillations in a Heterostructure of Graphene on a Proximate Quantum Spin Liquid

Contact Info

Product

Resources

About