Effect of impurity substitution on band structure and mass renormalization of the correlatedFeTe0.5Se0.5superconductor

Abstract

Using angle-resolved photoemission spectroscopy (ARPES), we studied the effect of the impurity potential on the electronic structure of FeTe 0.5 Se 0.5 superconductor by substituting 10% of Ni for Fe, which leads to an electron doping of the system. We could resolve three hole pockets near the zone center and an electron pocket near the zone corner in the case of FeTe 0.5 Se 0.5 , whereas only two hole pockets near the zone center and an electron pocket near the zone corner are resolved in the case of Fe 0.9 Ni 0.1 Te 0.5 Se 0.5 , suggesting that the hole pocket having predominantly the xy orbital character is very sensitive to the impurity scattering. Upon electron doping, the size of the hole pockets decreases and the size of the electron pockets increases as compared to the host compound. However, the observed changes in the size of the electron and hole pockets are not consistent with the rigid-band model. Moreover, the effective mass of the hole pockets is reduced near the zone center and of the electron pockets is increased near the zone corner in the doped Fe 0.9 Ni 0.1 Te 0.5 Se 0.5 as compared to FeTe 0.5 Se 0.5 . We refer these observations to the changes of the spectral function due to the effect of the impurity potential of the dopants.

Pressure-induced structural transition and huge enhancement of superconducting properties of single-crystal Fe0.99Ni0.01Se0.5Te0.5 unconventional superconductor

“…Further, application of pressure up to 20.6 GPa, the normal state resistivity decreases, and enhancement of metallic nature is observed and it is due to the alignment of distorted structure and resulting in an increase of the number of charge carriers at the Fermi level of this system [40]. In general, there is a trend in the decrease of electrical resistivity with pressure that would imply the reduction of net electron-phonon scattering and it indicate that the densities of states (DOS) is reduced at the Fermi surface and leads to enhancement of metallic behaviour in Fe0.99Ni0.01Fe0.5Te0.5.…”

Fermi surface and effective masses in photoemission response of the (Ba1−x K x )Fe2As2 superconductor

“…This is especially true if one tries to explain angle-resolved photoemission (ARPES) spectra of the iron pnictides 6 – 13 . In this context a significant discrepancy between the effective masses derived from experimental ARPES spectra and from LDA band structure calculations was reported 11 , 13 , 14 . Correct trends in the effective masses can be observed using dynamical a mean-field theory (DMFT) approach which quantifies the importance of correlation effects for the iron pnictides 15 , 16 .…”

“…[6][7][8][9][10][11][12][13] In this context a significant discrepancy between the effective masses derived from experimental ARPES spectra m * exp and from LDA band structure calculations m * LDA was reported. 11,13,14 Correct trends in the effective masses can be observed using dynamical a mean-field theory (DMFT) approach which quantifies the importance of correlation effects for the iron pnictides. 15,16 Various advanced approaches have been applied in the field, accounting for different phenomena.…”

Fast Suppression of Superconductivity with Fe Site Ni Substitution in Fe 1 − x Ni x Se0.5Te0.5 (x = 0.0 to 0.20) Single Crystals

“…Following the protocol [23], we have grown single crystals of series Fe 1-x Ni x Se 0.5 Te 0.5 . Very recently, the pure (superconducting) and Fe site 10at% Ni doped (non superconducting) FeSe 0.5 Te 0.5 flux free crystals of ours were exposed to ARPES (Angle Resolved Photo Electron Spectroscopy) studies [24]. A decrease in the size of hole pockets near the zone center and an increase in the size of electron pockets near the zone corner was seen with Fe site Ni doping in FeSe 0.5 Te 0.5 , thus suggesting an effective electron doping [24].…”