Experimental time-resolved photoemission andab initiostudy of lifetimes of excited electrons in Mo and Rh

Abstract

We have studied the relaxation dynamics of optically excited electrons in molybdenum and rhodium by means of time resolved two-photon photoemission spectroscopy (TR-2PPE) and ab initio electron self-energy calculations performed within the GW and GW + T approximations. Both theoretical approaches reproduce qualitatively the experimentally observed trends and differences in the lifetimes of excited electrons in molybdenum and rhodium. For excitation energies exceeding the Fermi energy by more than 1 eV, the GW + T theory yields lifetimes in quantitative agreement with the experimental results. As one of the relevant mechanisms causing different excited state lifetime in Mo and Rh we identify the occupation of the 4d bands. An increasing occupation of the 4d bands results in an efficient decrease of the lifetime even for rather small excitation energies of a few 100 meV.

Hot electron lifetimes in metals probed by time-resolved two-photon photoemission

“…Next to enhanced screening, this peculiarity opens up new channels for e-e scattering processes potentially causing an overall decrease in the inelastic lifetime. Advanced theoretical approaches [62,70,122] and TR-2PPE experiments [195] confirm this general trend. More specifically, details such as occupation, width and shape of the d-bands dominantly affect the lifetime and can finally result in a behavior which is fundamentally different from an FLT type behavior [196,197].…”

“…6.1 shows the density of states of the 4d-transition metal molybdenum [195]. At an overall width of %11 eV the partial DOS associated with the d-bands extends to excitation energies of about 5 eV above E F .…”

“…Fig. 6.2 compares TR-2PPE data sets from polycrystalline Mo samples [195] and momentum averaged lifetime results obtained by different theoretical GW-based approaches [70,195].…”

Theoretical study of quasiparticle inelastic lifetimes as applied to aluminum

“…͑21͔͒ the approximation W ͑q͒ =2W͑q ,0͒ / 3 makes ab initio calculations of the T-matrix contribution feasible. 41 The use of the local interaction of Ref. 22 ͑see the "ZCE" curve͒ yields the T-matrix contribution that differs significantly in value and behavior.…”

Wave-diffusion theory of spin transport in metals after ultrashort-pulse excitation

“…In particular, spin relaxation in semiconductors has been investigated, 3,4 lifetimes in metals have been measured, 5 and ultrafast changes of magnetic order by optical pulses have been discovered. 6,7 Very recently there has been rapidly growing interest in studies that combine ultrafast optical excitation and detection with spin transport phenomena.…”