Measurement of the c-axis optical reflectance of AFe2As2 (A=Ba, Sr) single crystals: evidence of different mechanisms for the formation of two energy gaps.
We present the c-axis optical reflectance measurement on single crystals of BaFe2As2 and SrFe2As2, the parent compounds of FeAs based superconductors. Different from the ab-plane optical response where two distinct energy gaps were observed in the spin-density-wave (SDW) state, only the smaller energy gap could be seen clearly for E∥c axis. The very pronounced energy gap structure seen at a higher energy scale for E∥ab plane is almost invisible. We propose a novel picture for the band structure evolution across the SDW transition and suggest different driving mechanisms for the formation of the two energy gaps.
Chen
Z G
ZG
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Dong
T
T
Ruan
R H
RH
Hu
B F
BF
Cheng
B
B
Hu
W Z
WZ
Zheng
P
P
Fang
Z
Z
Dai
X
X
Wang
N L
NL