Dynamical conductivity of a two-layered structure with electron-acoustic phonon coupling

Upon considering the three interactions namely, the electron–acoustic phonon, the electron–optical phonon and the Coulomb, the analytical solutions for the energy gap equation allows one to determine the electronic structure parameters to discuss the behavior of superconducting transition temperature (Tc) and isotope effect coefficient (α) for layered structure YNi2 B2C. Tc of 17 K is estimated for YNi2B2C with electron–acoustic phonon (λac) = 0.31, electron–optical phonon (λop) = 0.1 and Coulomb screening parameter (μ*) = 0.126 indicating that the YNi2B2C superconductor is in the intermediate coupling regime. To correlate the Tc with various coupling strengths as λac, λop and μ*, we present curves of Tc with them. The present approach also explains the conditions for the Boron and Carbon isotope effect. The negative pressure coefficient of Tc in this layered material is attributed to the contraction along c-axis under hydrostatic pressure. We suggest from these results that both the acoustic and optical phonons within the framework of a three-square well scheme consistently explains the effective electron–electron interaction leading to superconductivity in layered structure YNi2B2C.

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Giant many-body enhancement of low temperature thermal-electron–acoustic-phonon coupling in semiconductor quantum wires

Physical Review Letters ◽

10.1103/physrevlett.70.2593 ◽

1993 ◽

Vol 70 (17) ◽

pp. 2593-2596 ◽

Cited By ~ 26

Author(s):

J. R. Senna ◽

S. Das Sarma

Keyword(s):

Low Temperature ◽

Acoustic Phonon ◽

Quantum Wires ◽

Phonon Coupling ◽

Many Body ◽

Thermal Electron ◽

Electron Acoustic ◽

Body Enhancement

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Acoustic phonon lifetimes limit thermal transport in methylammonium lead iodide

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1812227115 ◽

2018 ◽

Vol 115 (47) ◽

pp. 11905-11910 ◽

Cited By ~ 27

Author(s):

Aryeh Gold-Parker ◽

Peter M. Gehring ◽

Jonathan M. Skelton ◽

Ian C. Smith ◽

Dan Parshall ◽

...

Keyword(s):

Lattice Dynamics ◽

Acoustic Phonon ◽

Optoelectronic Devices ◽

High Energy ◽

High Energy Resolution ◽

Phonon Coupling ◽

Lead Iodide ◽

Phonon Modes ◽

Electron Phonon Coupling ◽

Methylammonium Lead Iodide

Hybrid organic–inorganic perovskites (HOIPs) have become an important class of semiconductors for solar cells and other optoelectronic applications. Electron–phonon coupling plays a critical role in all optoelectronic devices, and although the lattice dynamics and phonon frequencies of HOIPs have been well studied, little attention has been given to phonon lifetimes. We report high-precision momentum-resolved measurements of acoustic phonon lifetimes in the hybrid perovskite methylammonium lead iodide (MAPI), using inelastic neutron spectroscopy to provide high-energy resolution and fully deuterated single crystals to reduce incoherent scattering from hydrogen. Our measurements reveal extremely short lifetimes on the order of picoseconds, corresponding to nanometer mean free paths and demonstrating that acoustic phonons are unable to dissipate heat efficiently. Lattice-dynamics calculations using ab initio third-order perturbation theory indicate that the short lifetimes stem from strong three-phonon interactions and a high density of low-energy optical phonon modes related to the degrees of freedom of the organic cation. Such short lifetimes have significant implications for electron–phonon coupling in MAPI and other HOIPs, with direct impacts on optoelectronic devices both in the cooling of hot carriers and in the transport and recombination of band edge carriers. These findings illustrate a fundamental difference between HOIPs and conventional photovoltaic semiconductors and demonstrate the importance of understanding lattice dynamics in the effort to develop metal halide perovskite optoelectronic devices.

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