Ultrafast quasiparticle dynamics in the heavy-fermion compound YbRh2Si2

作者：Kummer K^*; Vyalikh D V; Rettig L; Cortes R; Kucherenko Yu; Krellner C; Geibel C; Bovensiepen U; Wolf M; Molodtsov S L

来源：Physical Review B, 2012, 86(8): 085139.

DOI：10.1103/PhysRevB.86.085139

Understanding strongly correlated rare-earth intermetallic compounds requires knowledge of the nature of the fermionic quasiparticles in states near the Fermi level E-F. We report on a pump-probe experiment using femtosecond time- and angle-resolved photoemission spectroscopy to determine lifetimes of hot quasiparticles in the heavy-fermion compound YbRh2Si2. An unoccupied band with electronlike dispersion and a band bottom 0.2 eV above E-F was identified at (Gamma) over bar, in agreement with band structure calculations for the subsurface region. Hot quasiparticle lifetimes from 30 to 80 fs were found for energies between 0.4 and 0.1 eV above E-F. These lifetimes generally follow the typical monotonous increase towards E-F, in agreement with earlier studies on Yb and Rh elemental metals. However, at normal emission the lifetimes at around 0.2 eV exceed this trend by about +20 fs. This difference decreases with increasing photoemission angle and can be assigned to the particular band that is probed in YbRh2Si2. Potential microscopic scenarios are discussed.

• 出版日期2012-8-24