As-75 NMR study of single crystals of the heavily overdoped pnictide superconductors Ba1-xKxFe2As2 (x=0.7 and 1)

作者：Zhang, S W^*; Ma, L; Hou, Y D; Zhang, J; Xia, T L; Chen, G F; Hu, J P; Luke, G M; Yu, W

来源：PHYSICAL REVIEW B, 2010, 81(1): 012503.

DOI：10.1103/PhysRevB.81.012503

• COEXISTENCE
• GAPS

We performed As-75 NMR studies on two overdoped high-quality Ba1-xKxFe2As2 (x=0.7 and 1.0) single crystals. In the normal states, we found a dramatic increase in the spin-lattice relaxation (1/T-75(1)) from the x =0.7 to the x=1.0 samples. In KFe2As2, the ratio of 1/(T1TKn2)-T-75, where K-75(n) is the Knight shift, increases as temperature drops. These results indicate the existence of another type of spin fluctuations in KFe2As2 which is accustomed to being treated as a simple Fermi liquid. In the superconducting state, the temperature scalings of 1/T-75(1) below T-c in the overdoped samples are significantly different from those in the under or optimally doped ones. A power-law scaling behavior 1/(T1T)-T-75 similar to T-0.5 is observed, which indicates universal strong low-energy excitations in the overdoped hole-type superconductors.

• 出版日期2010-1
• 单位中国人民大学; 华北电力大学