PATH-INTEGRAL APPROACH FOR ELECTRON–PHONON INTERACTION EFFECTS IN HARMONIC QUANTUM DOTS

1996 ◽  
Vol 10 (22) ◽  
pp. 2781-2796 ◽  
Author(s):  
SOMA MUKHOPADHYAY ◽  
ASHOK CHATTERJEE
Keyword(s):  
Quantum Dots ◽  
Path Integral ◽  
State Energy ◽  
Coupling Parameter ◽  
Three Dimensions ◽  
Integral Approach ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Parabolic Confinement

We use the Feynman–Haken path-integral formalism to obtain the polaronic correction to the ground state energy of an electron in a polar semiconductor quantum dot with parabolic confinement in both two and three dimensions. We perform calculations for the entire range of the electron–phonon coupling parameter and for arbitrary confinement length. We apply our results to several semiconductor quantum dots and show that the polaronic effect in some of these dots can be considerably large if the dot sizes are made smaller than a few nanometers.

scholarly journals Impact of electron–phonon coupling on electron transport through T-shaped arrangements of quantum dots in the Kondo regime

2021 ◽  
Vol 12 ◽  
pp. 1209-1225
Author(s):  
Patryk Florków ◽  
Stanisław Lipiński
Keyword(s):  
Quantum Dots ◽  
Mean Field ◽  
Strongly Correlated ◽  
Interference Effects ◽  
Phonon Coupling ◽  
Many Body ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Kondo Effects ◽  
Electron Phonon Coupling

We calculate the conductance through strongly correlated T-shaped molecular or quantum dot systems under the influence of phonons. The system is modelled by the extended Anderson–Holstein Hamiltonian. The finite-U mean-field slave boson approach is used to study many-body effects. Phonons influence both interference and correlations. Depending on the dot unperturbed energy and the strength of electron–phonon interaction, the system is occupied by a different number of electrons that effectively interact with each other repulsively or attractively. This leads, together with the interference effects, to different spin or charge Fano–Kondo effects.

Variational Path-Integral Study on a Bipolaron in a Parabolic Quantum Wire or Well

2003 ◽  
Vol 17 (22n24) ◽  
pp. 4332-4337 ◽  
Author(s):  
Yong-Hong Ruan ◽  
Qing-Hu Chen ◽  
Zheng-Kuan Jiao
Keyword(s):  
Path Integral ◽  
Quantum Wire ◽  
State Energy ◽  
Integral Formula ◽  
Dielectric Constants ◽  
Coupling Constant ◽  
Phonon Coupling ◽  
Potential Strength ◽  
Electron Phonon Coupling ◽  
Present Formalism

The expression of the ground-state energy of a bipolaron in a parabolic quantum wire or well is derived within the framework of Feynman variational path-integral theory. We obtain a general result with arbitrary electron-phonon coupling constant, confining potential strength, and ratio of dielectric constants, which could be used for further numerical calculation of bipolaron properties. Moreover, it is shown that all previous path-integral formula for a bipolaron in a parabolic quantum wire, quantum well or quantum dot can be recovered in the present formalism.

Thermal Shifts and Electron-Phonon Coupling Parameters for the Three Luminescence Lines of 5DJ→7FJ in SrFCl:Sm2+ Crystal

2018 ◽  
Vol 73 (7) ◽  
pp. 657-659 ◽  
Author(s):  
Yang Mei ◽  
Hong-Gang Liu ◽  
Wen-Chen Zheng
Keyword(s):  
Coupling Parameter ◽  
Blue Shift ◽  
Simple Expression ◽  
Spectral Lines ◽  
Phonon Coupling ◽  
Lattice Thermal Expansion ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Coupling Parameters ◽  
Vibrational Contribution

AbstractThe thermal blue shifts of three spectral lines E1(5D0→7F0), E2(5D0→7F1), and E3(5D1→7F0) in SrFCl:Sm2+ crystal are investigated by a complete expression consisting of both the static contribution due to lattice thermal expansion and the vibrational contribution owing to electron-phonon interaction. The obtained true electron-phonon coupling parameters α′ in both sign and magnitude are considerably different from the apparent electron-phonon coupling parameters α acquired in the previous paper by considering only the vibrational contribution. It is suggested that differing from the simple expression including only the vibrational contribution (many authors thought that it cannot be used to explain the thermal blue shifts), the complete expression containing both the vibrational and static contributions is effective in the studies of thermal shift (whether red shift or blue shift) and true electron-phonon coupling parameter for a spectral line in crystals.

scholarly journals Translation-Invariant Excitons in a Phonon Field

2021 ◽  
Vol 6 (2) ◽  
pp. 20
Author(s):  
Victor D. Lakhno
Keyword(s):  
State Energy ◽  
Emission Spectra ◽  
Large Radius ◽  
Phonon Coupling ◽  
Translation Invariant ◽  
Phonon Field ◽  
Electron Phonon Interaction ◽  
Electron Phonon Coupling ◽  
Invariant Description ◽  
Nonzero Contribution

Large-radius excitons in polar crystals are considered. It is shown that translation invariant description of excitons interacting with a phonon field leads to a nonzero contribution of phonons into the exciton ground state energy only in the case of weak or intermediate electron-phonon coupling. A conclusion is made that self-trapped excitons cannot exist in the limit of strong coupling. Peculiarities of the absorption and emission spectra of translation invariant excitons in a phonon field are discussed. Conditions when the hydrogen-like exciton model remains valid in the case of electron-phonon interaction are found.

Path Integral Calculations of Particle Self-Energy and Effective Mass in Coulomb Systems

1997 ◽  
Vol 11 (04) ◽  
pp. 129-138 ◽  
Author(s):  
V. Sa-Yakanit ◽  
V. D. Lakhno ◽  
Klaus Haß
Keyword(s):  
Effective Mass ◽  
Path Integral ◽  
State Energy ◽  
Coulomb Systems ◽  
Integral Approach ◽  
Coupling Region ◽  
Self Energy ◽  
Consistent Approximation ◽  
A Value ◽  
Wide Range

The generalized path integral approach is applied to calculate the ground state energy and the effective mass of an electron-plasmon interacting system for a wide range of densities. It is shown that in the self-consistent approximation an abrupt transition between the weak coupling and the strong coupling region of interaction exists. The transition occurs at low electron densities according to a value of 418 for rs, when Wigner crystallization is possible. For densities of real metals, the electron bandwidth is calculated and a comparison with experimental results is given.

scholarly journals Electron-Phonon Coupling Parameter of Ferromagnetic Metal Fe and Co

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2755
Author(s):  
Kyuhwe Kang ◽  
Gyung-Min Choi
Keyword(s):  
Coupling Parameter ◽  
Critical Role ◽  
Circuit Modeling ◽  
Metallic Materials ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Complicated Process ◽  
G Value ◽  
Non Equilibrium

The electron-phonon coupling (g) parameter plays a critical role in the ultrafast transport of heat, charge, and spin in metallic materials. However, the exact determination of the g parameter is challenging because of the complicated process during the non-equilibrium state. In this study, we investigate the g parameters of ferromagnetic 3d transition metal (FM) layers, Fe and Co, using time-domain thermoreflectance. We measure a transient increase in temperature of Au in an FM/Au bilayer; the Au layer efficiently detects the strong heat flow during the non-equilibrium between electrons and phonons in FM. The g parameter of the FM is determined by analyzing the temperature dynamics using thermal circuit modeling. The determined g values are 8.8–9.4 × 1017 W m−3 K−1 for Fe and 9.6–12.2 × 1017 W m−3 K−1 for Co. Our results demonstrate that all 3d transition FMs have a similar g value, in the order of 1018 W m−3 K−1.

TRANSITION FREQUENCY OF STRONG-COUPLING IMPURITY BOUND POLARON IN AN ASYMMETRIC QUANTUM DOT

2012 ◽  
Vol 11 (03) ◽  
pp. 1250026 ◽  
Author(s):  
CHENG-SHUN WANG ◽  
YU-FANG CHEN ◽  
JING-JIN XIAO
Keyword(s):  
Excited State ◽  
Coupling Strength ◽  
State Energy ◽  
Transition Frequency ◽  
Phonon Coupling ◽  
Excited State Energy ◽  
Bound Polaron ◽  
Asymmetric Quantum Dot ◽  
Asymmetric Quantum ◽  
Electron Phonon Coupling

Properties of the excited state of strong-coupling impurity bound polaron in an asymmetric quantum dot are studied by using linear combination operator and unitary transformation methods. The first internal excited state energy, the excitation energy and the transition frequency between the first internal excited and the ground states of the impurity bound polaron as functions of the transverse and the longitudinal effective confinement lengths of the dot, the electron–phonon coupling strength and the Coulomb bound potential were derived. Our numerical results show that they will increase with decreasing the effective confinement lengths, due to interesting quantum size confining effects. But they are an increasing functions of the Coulomb bound potential. The first internal excited state energy is a decreasing function of the electron–phonon coupling strength whereas the transition frequency and the excitation energy are an increasing one of the electron–phonon coupling strength.

scholarly journals Charge order lock-in by electron-phonon coupling in La1.675Eu0.2Sr0.125CuO4

2021 ◽  
Vol 7 (27) ◽  
pp. eabg7394
Author(s):  
Qisi Wang ◽  
Karin von Arx ◽  
Masafumi Horio ◽  
Deepak John Mukkattukavil ◽  
Julia Küspert ◽  
...  
Keyword(s):  
Wave Vector ◽  
Charge Order ◽  
Charge Ordering ◽  
Electron Interaction ◽  
Phonon Coupling ◽  
Electron Phonon Interaction ◽  
Self Energy ◽  
Electron Phonon Coupling ◽  
Charge Stripe ◽  
Lock In

Charge order is universal to all hole-doped cuprates. Yet, the driving interactions remain an unsolved problem. Electron-electron interaction is widely believed to be essential, whereas the role of electron-phonon interaction is unclear. We report an ultrahigh-resolution resonant inelastic x-ray scattering (RIXS) study of the in-plane bond-stretching phonon mode in stripe-ordered cuprate La1.675Eu0.2Sr0.125CuO4. Phonon softening and lifetime shortening are found around the charge ordering wave vector. In addition to these self-energy effects, the electron-phonon coupling is probed by its proportionality to the RIXS cross section. We find an enhancement of the electron-phonon coupling around the charge-stripe ordering wave vector upon cooling into the low-temperature tetragonal structure phase. These results suggest that, in addition to electronic correlations, electron-phonon coupling contributes substantially to the emergence of long-range charge-stripe order in cuprates.

scholarly journals A PATH-INTEGRAL APPROACH FOR BOSONIC EFFECTIVE THEORIES FOR FERMION FIELDS IN FOUR AND THREE DIMENSIONS

2000 ◽  
Vol 15 (05) ◽  
pp. 755-770 ◽  
Author(s):  
LUIZ C. L. BOTELHO
Keyword(s):  
Path Integral ◽  
Infrared Region ◽  
Three Dimensions ◽  
Integral Approach ◽  
Ultraviolet Region ◽  
Fermion Field ◽  
Massive Fermion ◽  
Bosonic Field ◽  
Fermion Fields ◽  
Effective Theories

We study four-dimensional effective bosonic field theories for (A) massive fermion field in the infrared region and (B) massive fermion in the ultraviolet region by using an appropriate fermion path integral chiral variable change and (C) Polyakov's Fermi–Bose transmutation in the 3D-Abelian Thirring model and its triviality as a quantum field theory.

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