Inelastic quasiparticle lifetimes of the Shockley surface state band on Ni(111)

Abstract

We present a study of the low-energy quasiparticle lifetimes of the Shockley surface state on the Ni(111) surface with scanning tunnelling spectroscopy. By measuring the coherence length of the decaying standing wave pattern at straight step edges electron and hole lifetimes have been determined. The values of the lifetime measured on this ferromagnetic surface show to be considerable smaller than the values obtained from noble metal surfaces. This is explained by differences in the electron density of states at the Fermi energy but has to include substantial spin-flip scattering. Furthermore hole lifetimes appear to be larger than electron lifetimes with the same excitation energy. Although only results for the majority spin component are presented, a spin-dependent selfenergy is expected. PACS 72.15.

Real-space visualization of quasiparticle dephasing near the Planckian limit in the Dirac line node material ZrSiS

“…The τ values for the surface states of nonmagnetic Ag and Bi 2 Se 3 lie well above the Planckian limit [33,34,42]. Ferromagnetic Ni has lower values of τ closer to the Planckian limit [32], especially on the electron side near 100 meV, and this suppression relative to nonmagnetic Ag was attributed to spin-flip scattering. ZrSiS has the shortest quasiparticle lifetimes, which lie just at the Planckian limit.…”

“…Spin-orbit coupling was included in an additional non-self-consistent step. (g) for ZrSiS, Ni(111) [32], Ag(111) [33], and Bi 2 Se 3 [34]. The dashed line denotes the Planckian limit.…”

“…At low measurement temperatures, the measured lifetime predominantly reflects inelastic electron scattering, rather than inelastic phonon scattering. Despite the potential of this technique, its application has been largely limited to the surface states of a few noble and transition metals [31][32][33], as well as that of the topological insulator Bi 2 Se 3 [34],…”