Electron-electron scattering and nonequilibrium noise in sharvin contacts

Nagaev, K. É.; Krishtop, Tatiana; Sergeeva, N. Yu.

doi:10.1134/s0021364011130145

Cited by 21 publications

(33 citation statements)

References 13 publications

(18 reference statements)

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“…At increasing dc bias voltage |V | across the PC we observe that R diff decreases by almost a factor of 2, roughly linear in V (solid line). This observation is qualitatively analogous to the T -dependence of the linear response PC resistance 9 and signifies a drag-like nonlinear contribution |δI| ∼ V 2 in the e-e scattering scenario 6 . Similar behavior is observed in all our samples, see the inset of fig.…”

Section: -7supporting

confidence: 64%

“…In the linear response regime the PC conductance was predicted to increase linearly with T in qualitative agreement with experiments 8,9 . In the nonlinear transport regime the same mechanism should give rise to the excess current contribution in the PC |δI| ∝ V 2 and the excess shot noise with a spectral density of 2|eδI| 6 . These hallmarks of the drag-like e-e scattering mechanism we attempt to observe here.…”

Section: -7mentioning

confidence: 92%

“…Counterintuitively, such extra scattering gives rise to the decrease of R diff , which perfectly fits in the e-e scattering scenario of the nonlinear transport in quasi-classical PCs 6 . At T = 0 uncorrelated scattering events between the carriers of the incident and outgoing beams result in a non-equilibrium electronic distribution and give rise to the Poissonian extra noise 6 . Sub-poissonian extra noise in fig.…”

Section: -7mentioning

confidence: 99%

“…In Ref. 6 , the e-e scattering is assumed weak compared to the elastic scattering, which determines the mean-free path and cuts-off the logarithmic divergence of the collision integral. In contrast, we estimate…”

Section: -7mentioning

confidence: 99%

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Nonlinear transport and noise thermometry in quasiclassical ballistic point contacts

et al. 2014

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We study nonlinear transport and non-equilibrium current noise in quasi-classical point contacts (PCs) defined in a low-density high-quality two-dimensional electron system in GaAs. At not too high bias voltages V across the PC the noise temperature is determined by a Joule heat power and almost independent on the PC resistance that can be associated with a self-heating of the electronic system. This commonly accepted scenario breaks down at increasing V , where we observe extra noise accompanied by a strong decrease of the PC's differential resistance. The spectral density of the extra noise is roughly proportional to the nonlinear current contribution in the PC δS ≈ 2F * |eδI| ∼ V 2 with the effective Fano factor F * < 1, indicating that a random scattering process is involved. A small perpendicular magnetic field is found to suppress both δI and δS. Our observations are consistent with a concept of a drag-like mechanism of the nonlinear transport mediated by electronelectron scattering in the leads of quasi-classical PCs.The Landauer's approach 1 accounts for elastic scattering of the charge carriers (electrons) off the potential inhomogeneities and is applicable in quasi onedimensional conductors shorter than the phase-coherence length. Within this framework the temperature (T ) and bias (V ) dependencies of the conductance are caused solely by the averaging of the energy-dependent scattering matrices 2 . Being a random process the resulting reflection (backscattering) of the electrons at the conductor produces non-equilibrium fluctuations of the electric current (shot noise) 3 . Qualitatively, increasing backscattering reduces the current and increases the relative current fluctuation. The same holds true for a backscattering owing to the electron-phonon interaction in classical metallic point contacts (PCs) 4 .A different concept was recently proposed in Refs. 5-7for inelastic electron-electron scattering (e-e scattering) nearby a quasi-classical ballistic PC. Counter-intuitively, a reduction of the mean-free path owing to the e-e scattering was predicted to give rise to an increase of the PC conductance 5 . In contrast to the backscattering scenario, this can be understood in terms of a drag-like interaction between the electrons of the incident and outgoing beams mediated by a non-equilibrium electronic distribution nearby the PC. In the linear response regime the PC conductance was predicted to increase linearly with T in qualitative agreement with experiments 8,9 . In the nonlinear transport regime the same mechanism should give rise to the excess current contribution in the PC |δI| ∝ V 2 and the excess shot noise with a spectral density of 2|eδI|6 . These hallmarks of the drag-like e-e scattering mechanism we attempt to observe here.So far experimental observations of the leads-related noise were limited to 1/f -like noise in classical metallic PCs with signatures of phonon emission 10 and trivial self-heating effect owing to Joule heat dissipation in semiconductor PCs 11 and diffusive metallic nanowi...

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Section: -7supporting

confidence: 64%

Section: -7mentioning

confidence: 92%

Section: -7mentioning

confidence: 99%

Section: -7mentioning

confidence: 99%

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Nonlinear transport and noise thermometry in quasiclassical ballistic point contacts

et al. 2014

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“…In Table III, we provide numerical estimates of the phase boundary for J 3 = 0, i.e., along the J 1 -J 2 line obtained by PFFRG and other numerical approaches. The observation that for FM J 1 the stripe AF order extends at the expense of FM order follows from the fact that quantum fluctuations, in general, do not alter the FM state (including its ground state energy) as its an eigenstate of the Heisenberg exchange Hamiltonian and thus free of macroscopic zero-point vibrations [5,86], however, act on AF orders, e.g., by lowering their ground state energies. Hence, compared to the classical case, phase boundaries be-…”

Section: B Quantum Phase Diagrammentioning

confidence: 99%

Quantum paramagnetism and helimagnetic orders in the Heisenberg model on the body centered cubic lattice

et al. 2019

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We investigate the spin S = 1/2 Heisenberg model on the body centered cubic lattice in the presence of ferromagnetic and antiferromagnetic nearest-neighbor J1, second-neighbor J2, and third-neighbor J3 exchange interactions. The classical ground state phase diagram obtained by a Luttinger-Tisza analysis is shown to host six different (noncollinear) helimagnetic orders in addition to ferromagnetic, Néel, stripe and planar antiferromagnetic orders. Employing the pseudofermion functional renormalization group (PFFRG) method for quantum spins (S = 1/2) we find an extended nonmagnetic region, and significant shifts to the classical phase boundaries and helimagnetic pitch vectors caused by quantum fluctuations while no new long-range dipolar magnetic orders are stabilized. The nonmagnetic phase is found to disappear for S = 1. We calculate the magnetic ordering temperatures from PFFRG and quantum Monte Carlo methods, and make comparisons to available data. arXiv:1902.01179v1 [cond-mat.str-el]

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Cu, Pu and Fe High T c Superconductors: All the Same Mechanism

Wächter

2010

J Supercond Nov Magn

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The new iron based high T c superconductors with T c up to 55 K have stirred new interest in this field. It is consensus that the BCS mechanism is not able to explain the high T c 's. In the following we propose that spin holes in antiferromagnetic clusters combine to make nonmagnetic bipolarons, which can condense and lead to superconductivity.The discovery of high T c superconductivity in iron based Ln(O 1-x F x )FeAs (Ln = La, Ce, Pr, Nd, Sm, Gd) with T c from 25 -55 K has opened a new era of research [1-6] with materials, which are especially simple to prepare. Single crystals with T c of 53 K have been obtained for the Sm compound when grown under hydrostatic pressure of 30 kbar and T = 1350 -1450 C with x = 0.2 [7].

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Electron-electron scattering and nonequilibrium noise in sharvin contacts

Cited by 21 publications

References 13 publications

Nonlinear transport and noise thermometry in quasiclassical ballistic point contacts

Nonlinear transport and noise thermometry in quasiclassical ballistic point contacts

Quantum paramagnetism and helimagnetic orders in the Heisenberg model on the body centered cubic lattice

Cu, Pu and Fe High T c Superconductors: All the Same Mechanism

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