We present angle-integrated photoemission spectroscopy (PES) study of LaOFeAs:F (Tc = 26 K) and LaOFeP:F (Tc = 5 K) using He I line (h? = 21.2 eV) and laser (h? = 6.994 eV) as excitation light sources. We find quantitatively consistent results between the He I and the laser PES measurements: LaFeAsO:F exhibits a temperature-dependent pseudogap as large as ∼0.1 eV at 300 K, whereas LaFePO:F exhibits a ∼20-meV pseudogap. We discuss possible origin of the T -dependent pseudogap specifically observed in LaFeAsO:F through comparison with other materials that exhibit unusual T -dependent pseudogaps.
ASJC Scopus subject areas
- Physics and Astronomy(all)