Kinetic coefficients of metals ablated under the action of femtosecond laser pulses. Yu.V. Petrov*, N.A. Inogamov*, K.P. Migdal** * Landau Institute for Theoretical Physics, Chernogolovka ** All-Russia Research Institute of Automatics (VNIIA)

DoS for nickel and its parabolic approximation Also one constructed DoS for Al, Au, Cu, Fe, Pt, Ta using ABINIT* and Dmol³** *X. Gonze, B. Amadon, P.-M. Anglade et al., Computer Physics Communications, **

2-parabolic DoS Based on simple dispersion laws 4 independent parameters for one metal Gives the electronic thermodynamic properties such as a t. Explicit separation of the s- and d-branches of 2p DoS allows to distinguish the contributions of 2 conduction bands. The electronic properties evaluated from 2p DoS are in good agreement with the data of DFT calculations.

f-zone for Ta Data of Firefly* calculation** are used for the value of gap between f- and s-band *Alex A.Granovsky, Firefly version 7.1.G, www ** Andrei Mukhanov, private communication

DoS for Al, Au, Fe, Pt

2p DoS parameters for all 7 metals Metal Al Au -9,2-6,8-1,7110 Cu Fe -8,7-4,91,426 Ni -8,6-4,50,171,58,5 Pt Ta -8-4,65,923

Calculation of heat conductivity Solution of Boltzmann equation in time relaxation approximation leads to the expressions for frequency of collisions of electron with momentum. Frequencies of s-s and s-d collisions are used for calculation partial thermal conductivities.

Calculation of heat conductivity Thermodynamic values – from 2p partial DoS (s-branch). Frequency of electron-ion collision – from the experimental data* for electric resistivity (via Drude formula). Electron-electron collision frequencies find out from the expression in time relaxation approximation. *G. Pottlacher, High Temperature Thermophysical Properties of 22 Pure Metals, Keiper (2010).

Heat conductivity for 5 metals In 1T state and at room temperature heat conductivity is less than in order of magnitude ( )

Comparison with existing fitting* *D.S.Ivanov, L.V.Zhigilei. Phys.Rev.B, (2003). **N.A. Inogamov, Yu.V. Petrov. JETP, 137(3), pp (in Russian)

Calculation of electron-phonon coupling Bose-Einstein distribution for phonons The rate of energy exchange by Kaganov* et al formula Only longitudinal phonons are considered Phonon dispersion law in Debye approach The contributions of s- and d-band electrons in alpha are derived * M.I Kaganov, I.M. Lifshitz, L.V. Tanatarov. JETP. 31(232), 1956

Electron-phonon coupling of Al and Au for gold renormalized to experimental data at room T is in agreement with Lin*. *Zh. Lin, L.V. Zhigilei, V. Celli, Phys. Rev. B 77, (2008).

Electron-phonon coupling for Fe,Ni,Ta Sufficient difference between alpha Fe(3d 6 4s 2 ) and Ni(3d 8 4s 2 ) Data for Ni compared with Lin* *Zh. Lin, L.V. Zhigilei, V. Celli, Phys. Rev. B 77, (2008).

Conclusion The scheme for calculation of the electronic thermodynamic and kinetic properties for metals in 2T state. Electron heat conductivity and electron- phonon coupling are evaluated for 7 metals (Al, Au, Cu, Fe, Ni, Pt, Ta).

Outline Introduction. Interaction of femtosecond laser pulses with noble and transition metals: characteristic values, temporal stages, used approximations. Common basement for kinetic coefficient calculation: two-parabolic density of states. Assumptions, calculation scheme and results for calculation of thermal conductivity and electron-phonon coupling.

Introduction P ~ 20 GPa T 1 ~ 3000 K F ~ F abl (100 mJ/cm²) T e >> T 1 Nickel duration=0.1 ps time=1ps F abs =132 mJ/cm²

Introduction

Temporary stages 2T-stage It is necessary to know kinetic coefficients of metal on 2T-stage