Nonconservative dynamics in long atomic wires

Cunningham, B.; Todorov, Tchavdar N.; Dundas, Daniel

doi:10.1103/physrevb.90.115430

Cited by 15 publications

(25 citation statements)

References 25 publications

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“…Their vital role in maintaining the electronic device stability is further promoted at the nanoscale. Our understanding of the two closely related effects, especially their interplay in nanoand atomic conductors is still under development [2][3][4][5][6][7][8][9][10]. Several forces, present only in the nonequilibrium situation, have been discovered theoretically.…”

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confidence: 99%

Current-Induced Forces and Hot Spots in Biased Nanojunctions

et al. 2015

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We investigate theoretically the interplay of current-induced forces (CIFs), Joule heating, and heat transport inside a current-carrying nanoconductor. We find that the CIFs, due to the electron-phonon coherence, can control the spatial heat dissipation in the conductor. This yields a significant asymmetric concentration of excess heating (hot spot) even for a symmetric conductor. When coupled to the electrode phonons, CIFs drive different phonon heat flux into the two electrodes. First-principles calculations on realistic biased nanojunctions illustrate the importance of the effect.

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confidence: 99%

Current-Induced Forces and Hot Spots in Biased Nanojunctions

et al. 2015

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“…The behavior of the system under small displacements about a reference geometry can be understood from the dynamical response matrix [4,8] , where P is the sum of repulsive pair potentials and 7 8 is the expectation value of the force operator , with the electronic Hamiltonian. is non-Hermitian under current [8], and has anti-symmetric part ,…”

Section: Methodsmentioning

confidence: 99%

“…where I is the saturation current (time and spatially averaged steady-state bond current [8]) and A ∝ 1/= >? @ E .…”

Section: Dynamical Simulationsmentioning

confidence: 99%

“…The reason is the dense vibrational mode frequency spectra of these systems [8] together with their high conductivity. It is shown in [3,8] that current can couple near degenerate modes to create new modes that grow in time (referred to as waterwheel modes). In this paper we employ two methods for investigating NCF: a Landauer steady-state approach; and non-equilibrium, non-adiabatic molecular dynamics (MD) simulations.…”

Section: Introductionmentioning

confidence: 99%

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Length Matters: Keeping Atomic Wires in Check

2015

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Dynamical effects of non-conservative forces in long, defect free atomic wires are investigated. Current flow through these wires is simulated and we find that during the initial transient, the kinetic energies of the ions are contained in a small number of phonon modes, closely clustered in frequency. These phonon modes correspond to the waterwheel modes determined from preliminary static calculations. The static calculations allow one to predict the appearance of non-conservative effects in advance of the more expensive real-time simulations. The ion kinetic energy redistributes across the band as non-conservative forces reach a steady state with electronic frictional forces. The typical ion kinetic energy is found to decrease with system length, increase with atomic mass, and its dependence on bias, mass and length is supported with a pen and paper model. This paper highlights the importance of non-conservative forces in current carrying devices and provides criteria for the design of stable atomic wires.

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“…This requires the full non-adiabatic open-boundary molecular dynamics of Ref. [11], as opposed to the perturbative description of equation (9).…”

Section: Non-conservative Dynamics In Atomic Wiresmentioning

confidence: 99%

Non-conservative forces in bulk systems

Todorov

Cunningham

Dundas

et al. 2017

Materials Science and Technology

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The ability of electrons and phonons to equilibrate is fundamental to the thermodynamic and transport properties of solids. Nonetheless in mesoscopic systems sufficiently high current densities can lead to situations where the phonon subsystem can no longer reach a steady state. In previous work this phenomenon was connected with the demonstration that interatomic forces under current are non-conservative, with dramatic dynamical effects. Here we consider these effects in bulk systems. We arrive at a critical current density beyond which current flow results in the uncompensated stimulated emission of a blast of phonons.The result is illustrated with simulations of long atomic wires. It is hoped that the paper will stimulate research into the possible relevance of the effect to electropulsing.

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Nonconservative dynamics in long atomic wires

Cited by 15 publications

References 25 publications

Current-Induced Forces and Hot Spots in Biased Nanojunctions

Current-Induced Forces and Hot Spots in Biased Nanojunctions

Length Matters: Keeping Atomic Wires in Check

Non-conservative forces in bulk systems

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