Hydrodynamic Effects in Solids at Low Temperature

Gurzhi, R. N.

doi:10.1070/pu1968v011n02abeh003815

Cited by 370 publications

(339 citation statements)

References 2 publications

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“…3d, lending strong support to our analysis. The measured dependence G ν (T ) allows us to determine ν(T ) and l ee (T ) using equation (2). The results are shown in Fig.…”

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confidence: 74%

“…To avoid fitting parameters, we model the contact resistance as The figure shows that, after the phonon contribution is accounted for through R C , the resistance R (attributable to the narrowing itself) monotonically decreases with increasing T over the entire T range, in agreement with equation (2). The validity of this analysis is further confirmed by the fact that the extracted values of R were found to be independent of b (that is, insensitive to voltage probes positions relative to PCs; see Supplementary Fig.…”

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confidence: 76%

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Superballistic flow of viscous electron fluid through graphene constrictions

et al. 2017

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Electron-electron (e-e) collisions can impact transport in a variety of surprising and sometimes counterintuitive ways 1-6 . Despite strong interest, experiments on the subject proved challenging because of the simultaneous presence of di erent scattering mechanisms that suppress or obscure consequences of e-e scattering 7-11 . Only recently, su ciently clean electron systems with transport dominated by e-e collisions have become available, showing behaviour characteristic of highly viscous fluids 12-14 . Here we study electron transport through graphene constrictions and show that their conductance below 150 K increases with increasing temperature, in stark contrast to the metallic character of doped graphene 15 . Notably, the measured conductance exceeds the maximum conductance possible for free electrons 16,17 . This anomalous behaviour is attributed to collective movement of interacting electrons, which 'shields' individual carriers from momentum loss at sample boundaries 18,19 . The measurements allow us to identify the conductance contribution arising due to electron viscosity and determine its temperature dependence. Besides fundamental interest, our work shows that viscous e ects can facilitate high-mobility transport at elevated temperatures, a potentially useful behaviour for designing graphene-based devices.Graphene hosts a high-quality electron system with weak phonon coupling 20,21 such that e-e collisions can become the dominant scattering process at elevated temperatures, T . In addition, the electronic structure of graphene inhibits Umklapp processes 15 , which ensures that e-e scattering is momentum conserving. These features lead to a fluid-like behaviour of charge carriers, with the momentum taking on the role of a collective variable that governs local equilibrium. Previous studies of the electron hydrodynamics in graphene were carried out using the vicinity geometry and Hall bar devices of a uniform width. Anomalous (negative) voltages were observed, indicating a highly viscous flow, more viscous than that of honey 12,22,23 . In this report, we employ a narrow constriction geometry (Fig. 1a) which offers unique insight into the behaviour of viscous electron fluids. In particular, the hydrodynamic conductance through such constrictions becomes

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“…3d, lending strong support to our analysis. The measured dependence G ν (T ) allows us to determine ν(T ) and l ee (T ) using equation (2). The results are shown in Fig.…”

mentioning

confidence: 74%

mentioning

confidence: 76%

Superballistic flow of viscous electron fluid through graphene constrictions

et al. 2017

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“…A more intriguing alternative is that magnons undergo Poiseuille flow, predicted 50 years ago for both phonons and magnons [33,34,36], but observed only for phonons and only in exceptionally clean materials (e.g. crystalline 4 He [37]).…”

Section: B Ballistic Lattice and Magnon Thermal Conductivities Distimentioning

confidence: 99%

Ballistic magnon heat conduction and possible Poiseuille flow in the helimagnetic insulator Cu2OSeO3

et al. 2017

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We report on the observation of magnon thermal conductivity κm ∼ 70 W/mK near 5 K in the helimagnetic insulator Cu2OSeO3, exceeding that measured in any other ferromagnet by almost two orders of magnitude. Ballistic, boundary-limited transport for both magnons and phonons is established below 1 K, and Poiseuille flow of magnons is proposed to explain a magnon mean-free path substantially exceeding the specimen width for the least defective specimens in the range 2K < T < 10 K. These observations establish Cu2OSeO3 as a model system for studying longwavelength magnon dynamics.

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“…Below 22 K it varies quadratically with frequency (with slight deviations at the lowest frequencies, presumably the result of impurities in the sample raising the dc resistivity) which indicates the onset of purely Fermi-liquid-like behaviour. The resistivity of a Fermi liquid, where electron-electron umklapp scattering is the dominant mechanism, is the sum of two terms, one quadratic in frequency and the other quadratic in temperature [27]:…”

Section: Philmag4mentioning

confidence: 99%

Optical study of hybridization and hidden order in URu₂Si₂

Hall

Timusk

2014

Philosophical Magazine

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We summarize existing optical data of URu 2 Si 2 to clarify the nature of the hidden order transition in this heavy fermion metal. Hybridization develops between 50 K and 17.5 K, and a coherent Drude peak emerges which mirrors the changes in the dc resistivity. The Drude weight indicates that there is little change in the effective mass of these carriers in this temperature range. In addition, there is a flat background conductivity that develops a partial hybridization gap at 10 meV as the temperature is lowered, shifting spectral weight to higher frequencies above 300 meV. Below 30 K the carriers become increasingly coherent and Fermi-liquid-like as the hidden order transition is approached. The hidden order state in URu 2 Si 2 is characterized by multiple anisotropic gaps. The gap parameter ∆a = 3.2 meV in the ab-plane. In the c-direction, there are two distinct gaps with magnitudes of ∆ c1 = 2.7 meV and ∆ c2 = 1.8 meV. These observations are in good agreement with other spectroscopic measurements. Overall, the spectrum can be fit by a Dynes-type density of states model to extract values of the hidden order gap. The transfer of spectral weight strongly resembles what one sees in density wave transitions.

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Hydrodynamic Effects in Solids at Low Temperature

Cited by 370 publications

References 2 publications

Superballistic flow of viscous electron fluid through graphene constrictions

Superballistic flow of viscous electron fluid through graphene constrictions

Ballistic magnon heat conduction and possible Poiseuille flow in the helimagnetic insulator Cu2OSeO3

Optical study of hybridization and hidden order in URu₂Si₂

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Hydrodynamic Effects in Solids at Low Temperature

Cited by 370 publications

References 2 publications

Superballistic flow of viscous electron fluid through graphene constrictions

Superballistic flow of viscous electron fluid through graphene constrictions

Ballistic magnon heat conduction and possible Poiseuille flow in the helimagnetic insulator Cu2OSeO3

Optical study of hybridization and hidden order in URu2Si2

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Optical study of hybridization and hidden order in URu₂Si₂