Evolution of quasiparticle states with and without a Zn impurity in doped 122 iron pnictides

Article

关键词: ENERGY GAPS;    SUPERCONDUCTIVITY;    SURFACE;    WAVE;    BA0.6K0.4FE2AS2;    SYMMETRY;   

DOI  :  10.1103/PhysRevB.90.134501

来源: SCIE

【 摘 要 】

Based on a minimal two-orbital model [Tai et al., Europhys. Lett. 103, 67001 (2013)], which captures the canonical electron-hole-doping phase diagram of the iron-pnictide BaFe2As2, we study the evolution of quasiparticle states as a function of doping using the Bogoliubov-de Gennes equations with and without a single impurity. Analyzing the density of states of uniformly doped samples, we are able to identify the origin of the two superconducting gaps observed in optimally hole- or electron-doped systems. The local density of states (LDOS) is then examined near a single impurity in samples without antiferromagnetic order. The qualitative features of our results near the single impurity are consistent with a work based on a five-orbital model [T. Kariyado et al., J. Phys. Soc. Jpn. 79, 083704 (2010)]. Some of the results are consistent with recent angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy experiments. This further supports the validity of our two-orbital model in dealing with LDOS in the single-impurity problem. Finally, we investigate the evolution of the LDOS with doping near a single impurity in the unitary or strong scattering limit, such as Zn replacing Fe. The positions of the in-gap resonance peaks exhibited in our LDOS may indirectly reflect the evolution of the Fermi surface topology according to the phase diagram. Our prediction of in-gap states and the evolution of the LDOS near a strong scattering single impurity can be validated by further experiments probing the local quasiparticle spectrum.

【 授权许可】

Free