Electron–phonon coupling factor and electron heat capacity of 6H-SiC

2021 ◽  
pp. 1-8
Author(s):  
Wenlong Liao ◽  
Chaohui He ◽  
Huan He ◽  
Shang Tian ◽  
Yurong Bai
Keyword(s):  
Heat Capacity ◽  
Coupling Factor ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling

Influence of Inter- and Intraband Transitions to Electron Temperature Decay in Noble Metals After Short-Pulsed Laser Heating

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Patrick E. Hopkins
Keyword(s):  
Heat Capacity ◽  
Electron Temperature ◽  
Noble Metals ◽  
Coupling Factor ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Temperature Decay ◽  
Electron Heat ◽  
Electron Phonon Coupling ◽  
Pulsed Laser Heating

This work examines the effects of photonically induced interband excitations from the d-band to states at the Fermi energy on the electron temperature decay in noble metals. The change in the electron population in the d-band and the conduction band causes a change in electron heat capacity and electron-phonon coupling factor. In noble metals, due to the large d-band to Fermi energy separation, the contributions to electron heat capacity and electron-phonon coupling factor of intra- and interband transitions can be separated. The two temperature model describing electron-phonon heat transfer after short-pulsed laser heating is solved using the expressions for heat capacity and electron-phonon coupling factor after intra- and interband excitations, and the predicted electron temperature change of the intra- and interband excited electrons are examined. A critical fluence value is defined that represents the absorbed fluence needed to fill all available states at a given photon energy above the Fermi level. At high absorbed laser fluences and pulse energies greater than the interband transition threshold, the interband and intraband contributions to thermophysical properties differ and are shown to affect temporal electron temperature profiles.

Contributions of Inter- and Intraband Excitations to Electron Heat Capacity and Electron-Phonon Coupling in Noble Metals

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Patrick E. Hopkins
Keyword(s):  
Heat Capacity ◽  
Thermophysical Properties ◽  
Fermi Energy ◽  
Noble Metals ◽  
Coupling Factor ◽  
Energy Separation ◽  
Phonon Coupling ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling

This work examines the effects of photonically induced interband excitations from the d-band to states at the Fermi energy on thermophysical properties in noble metals. The change in the electron population in the d-band and the conduction band causes a change in electron heat capacity and electron-phonon coupling factor, which in turn impacts the evolution of the temperature after pulse absorption and electron thermalization. Expressions for heat capacity and electron-phonon coupling factor are derived for electrons undergoing both inter- and intraband transitions. In noble metals, due to the large d-band to Fermi energy separation, the contributions to electron heat capacity and electron-phonon coupling factor of intra- and interband transitions can be separated. At high absorbed laser fluences and pulse energies greater than the interband transition threshold, the interband and intraband contributions to thermophysical properties differ.

The Role of Thermal Excitation of D Band Electrons in Ultrafast Laser Interaction With Noble (Cu) and Transition (Pt) Metals

2007 ◽  
Author(s):  
Zhibin Lin ◽  
Leonid V. Zhigilei
Keyword(s):  
Heat Capacity ◽  
Coupling Factor ◽  
Ultrafast Laser ◽  
Thermal Excitation ◽  
Phonon Coupling ◽  
Laser Interaction ◽  
Electron Heat Capacity ◽  
Electron Heat ◽  
Electron Phonon Coupling ◽  
Temperature Dependences

The temperature dependences of the electron heat capacity and electron-phonon coupling factor for noble (Cu) and transition (Pt) metals are investigated based on the electron density of states (DOS) obtained from ab initio electronic structure calculations. For Cu, d band electrons could be thermally excited when the electron temperature exceeds ∼3000 K, leading to a significant increase, up to an order of magnitude, in the electron-phonon coupling factor and strong enhancement of the electron heat capacity away from the linear dependence on the electron temperature, which is commonly used in most of the current computational and theoretical investigations of ultrafast laser interactions with metals. Opposite to the case in Cu, the thermal excitation of d band electrons in Pt leads to a monotonic decrease of the electron-phonon coupling factor and contributes to significant negative deviations of the electron heat capacity from the linear dependence in the range of electron temperatures that are typically realized in ultrafast laser material processing applications. Strong and drastically different temperature dependences of the thermophysical properties predicted for Cu and Pt point to the importance of the electron DOS effects and the necessity of full consideration of thermal excitation of d band electrons for realistic modeling of short pulse laser interaction with noble and transition metals.

scholarly journals Ultrafast electron calorimetry uncovers a new long-lived metastable state in 1T-TaSe2 mediated by mode-selective electron-phonon coupling

2019 ◽  
Vol 5 (3) ◽  
pp. eaav4449 ◽  
Author(s):  
Xun Shi ◽  
Wenjing You ◽  
Yingchao Zhang ◽  
Zhensheng Tao ◽  
Peter M. Oppeneer ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Metastable State ◽  
Density Wave ◽  
Charge Order ◽  
Phonon Coupling ◽  
Phonon Modes ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Quantum Matter ◽  
Electron Phonon Coupling ◽  
Equilibrium Phases

Quantum materials represent one of the most promising frontiers in the quest for faster, lightweight, energy-efficient technologies. However, their inherent complexity and rich phase landscape make them challenging to understand or manipulate. Here, we present a new ultrafast electron calorimetry technique that can systematically uncover new phases of quantum matter. Using time- and angle-resolved photoemission spectroscopy, we measure the dynamic electron temperature, band structure, and heat capacity. This approach allows us to uncover a new long-lived metastable state in the charge density wave material 1T-TaSe2, which is distinct from all the known equilibrium phases: It is characterized by a substantially reduced effective total heat capacity that is only 30% of the normal value, because of selective electron-phonon coupling to a subset of phonon modes. As a result, less energy is required to melt the charge order and transform the state of the material than under thermal equilibrium conditions.

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