Disorder-Assisted Electron-Phonon Scattering and Cooling Pathways in Graphene

Song, Justin C. W.; Reizer, Michael; Levitov, L. S.

doi:10.1103/physrevlett.109.106602

Cited by 316 publications

(586 citation statements)

References 25 publications

(50 reference statements)

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“…(18) does not contribute to the continuity equations. At the same time, the electron-phonon interaction (that we have so far neglected) may lead to energy and imbalance relaxation processes [9,19,[39][40][41][42][43][44][45]. Taking into account the electronphonon collisions, we find the following continuity equations (see Appendix C for details):…”

Section: A Linear-response Equations In Graphenementioning

confidence: 99%

Hydrodynamics in graphene: Linear-response transport

et al. 2015

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We develop a hydrodynamic description of transport properties in graphene-based systems, which we derive from the quantum kinetic equation. In the interaction-dominated regime, the collinear scattering singularity in the collision integral leads to fast unidirectional thermalization and allows us to describe the system in terms of three macroscopic currents carrying electric charge, energy, and quasiparticle imbalance. Within this "three-mode" approximation, we evaluate transport coefficients in monolayer graphene as well as in double-layer graphene-based structures. The resulting classical magnetoresistance is strongly sensitive to the interplay between the sample geometry and leading relaxation processes. In small, mesoscopic samples, the macroscopic currents are inhomogeneous, which leads to a linear magnetoresistance in classically strong fields. Applying our theory to double-layer graphene-based systems, we provide a microscopic foundation for a phenomenological description of giant magnetodrag at charge neutrality and find the magnetodrag and Hall drag in doped graphene.

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Section: A Linear-response Equations In Graphenementioning

confidence: 99%

Hydrodynamics in graphene: Linear-response transport

et al. 2015

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“…Graphene offers a unique system where the typical distance for such carrier -lattice cooling can exceed the dimensions of the device 28 due to anomalously long lifetime of the hot carriers 29 . Electron cooling rates are believed to be sharply enhanced in the presence of disorder, however the precise mechanism of such enhancement is poorly understood 30 . To probe microscopic dissipation mechanisms in graphene we performed scanning thermometry in high-mobility graphene encapsulated in hexagonal boron-nitride.…”

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confidence: 99%

Nanoscale thermal imaging of dissipation in quantum systems

Halbertal

Cuppens

Shalom

et al. 2016

Nature

197

175

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Energy dissipation is a fundamental process governing the dynamics of physical, chemical, and biological systems. It is also one of the main characteristics distinguishing quantum and classical phenomena. In condensed matter physics, in particular, scattering mechanisms, loss of quantum information, or breakdown of topological protection are deeply rooted in the intricate details of how and where the dissipation occurs. Despite its vital importance the microscopic behavior of a system is usually not formulated in terms of dissipation because the latter is not a readily measureable quantity on the microscale. Although nanoscale thermometry is gaining much recent interest [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] , the existing thermal imaging methods lack the necessary sensitivity and are unsuitable for low temperature operation required for study of quantum systems. Here we report a superconducting quantum interference nano-thermometer device with sub 50 nm diameter that resides at the apex of a sharp pipette and provides scanning cryogenic thermal sensing with four orders of magnitude improved thermal sensitivity of below 1 µK/Hz 1/2 . The non-contact non-invasive thermometry allows thermal imaging of very low nanoscale energy dissipation down to the fundamental Landauer limit [16][17][18] of 40 fW for continuous readout of a single qubit at 1 GHz at 4.2 K. These advances enable observation of dissipation due to single electron charging of individual quantum dots in carbon nanotubes and reveal a novel dissipation mechanism due to resonant localized states in hBN encapsulated graphene, opening the door to direct imaging of nanoscale dissipation processes in quantum matter. 2 Investigation of energy dissipation on the nanoscale is of major fundamental interest for a wide range of disciplines from biological processes, through chemical reactions, to energy-efficient computing [1][2][3][4][5] . Study of dissipation mechanisms in quantum systems is of particular importance because dissipation demolishes quantum information. In order to preserve a quantum state the dissipation has to be extremely weak and hence hard to measure. As a figure of merit for detection of low power dissipation in quantum systems 16 we consider an ideal qubit operating at a typical readout frequency of 1 GHz. Landauer's principle states the lowest bound on energy dissipation in an irreversible qubit operation to be 0 = B ln 2, where B is Boltzmann's constant and is the temperature 17,18 . At = 4.2 K, 0 = 410 -23 J, several orders of magnitude below 10 -19 J of dissipation per logical operation in present day superconducting electronics and 10 -15 J in CMOS devices 19,20 . Hence the power dissipated by an ideal qubit operating at a readout rate of = 1 GHz will be as low as = 0 = 40.2 fW. The resulting temperature increase of the qubit will depend on its size and the thermal properties of the substrate. For example, a 120 × 120 nm 2 device on a 1 µm thick SiO 2 /Si substrate dissipating 40 fW will heat up by about 3 µK (Fig. 1). Suc...

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“…1c) when k B T g ≈ φ/2, dominating over acoustic and optical phonon cooling [12,13] in pristine graphene Schottky junctions; J ⊥ q also overwhelms in-plane (lateral) diffusive energy transport. We find that the values of J ⊥ q are competitive with disorder-assisted cooling [14][15][16] in more dirty devices.Graphene is essential to our proposal due to a unique combination of electronic characteristics. First, fast intraband Auger-type scattering [19,20] allows the absorbed photon energy flux, J in q , to be efficiently captured as heat by ambient carriers in graphene; this process results in a thermalized hot carrier distribution [19,20].…”

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confidence: 82%

“…These junctions are characterized by Schottky barriers φ that span two orders of magnitude φ ≈ 0.01−1 eV and exhibit in situ control through applied bias or by using gate potentials [7][8][9][10][11]. The wide range of φ achievable across the g/X interface, combined with the unique graphene photoresponse mediated by long-lived hot carriers (elevated electronic temperatures, T g , different from those of the lattice, T 0 [12][13][14][15][16][17]), make graphene Schottky junctions a prime target for accessing novel vertical energy transport regimes [18].…”

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confidence: 99%

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Enhanced Thermionic-Dominated Photoresponse in Graphene Schottky Junctions

Rodriguez-Nieva¹,

Dresselhaus²,

Song

2016

Nano Lett.

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Vertical heterostructures of van der Waals materials enable new pathways to tune charge and energy transport characteristics in nanoscale systems. We propose that graphene Schottky junctions can host a special kind of photoresponse which is characterized by strongly coupled heat and charge flows that run vertically out of the graphene plane. This regime can be accessed when vertical energy transport mediated by thermionic emission of hot carriers overwhelms electron-lattice cooling as well as lateral diffusive energy transport. As such, the power pumped into the system is efficiently extracted across the entire graphene active area via thermionic emission of hot carriers into a semiconductor material. Experimental signatures of this regime include a large and tunable internal responsivity R with a non-monotonic temperature dependence. In particular, R peaks at electronic temperatures on the order of the Schottky potential φ and has a large upper limit R ≤ e/φ (e/φ = 10 A/W when φ = 100 meV). Our proposal opens up new approaches for engineering the photoresponse in optically-active graphene heterostructures.Keywords: graphene; hot carriers; Schottky junction; photocurrent Vertical heterostructures comprising layers of van der Waals (vdW) materials have recently emerged as a platform for designer electronic interfaces [1]. Of special interest are heterostructures which feature tunable interlayer transport characteristics, as exemplified by g/X Schottky junctions [2-10]; here 'g' denotes graphene, and X is a semiconductor material, such as Si, MoS 2 or WSe 2 . These junctions are characterized by Schottky barriers φ that span two orders of magnitude φ ≈ 0.01−1 eV and exhibit in situ control through applied bias or by using gate potentials [7][8][9][10][11]. The wide range of φ achievable across the g/X interface, combined with the unique graphene photoresponse mediated by long-lived hot carriers (elevated electronic temperatures, T g , different from those of the lattice, T 0 [12-17]), make graphene Schottky junctions a prime target for accessing novel vertical energy transport regimes [18].Here we show that specially designed graphene Schottky junctions can host an enhanced thermionicdominated photoresponse driven by strongly coupled charge and energy currents. Such photoresponse proceeds, as illustrated in Fig. 1a, via the thermionic emission of graphene hot carriers with energy larger than the Schottky barrier. At steady state, an equal number of cold carriers are injected at the Fermi surface through an ohmic contact, giving a net flow of heat J ⊥ q out of the graphene electronic system balancing the energy pumped into the system. Strikingly, thermionic emission yields strong heat transport running vertically out of the hot electron system, which dominates over more conventional electronic cooling channels, e.g. electron-lattice cooling. Indeed, we find that J ⊥ q can be significant in graphene (see Fig. 1c) when k B T g ≈ φ/2, dominating over acoustic and optical phonon cooling [12,13] in pristine graphene Sch...

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Disorder-Assisted Electron-Phonon Scattering and Cooling Pathways in Graphene

Cited by 316 publications

References 25 publications

Hydrodynamics in graphene: Linear-response transport

Hydrodynamics in graphene: Linear-response transport

Nanoscale thermal imaging of dissipation in quantum systems

Enhanced Thermionic-Dominated Photoresponse in Graphene Schottky Junctions

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