Doping dependence of phase-separation morphology in (Sr, K)Fe2As2

作者：Wei F Y^*; Lv B; Chen F; Sasmal K; Shulman J; Xue Y Y; Chu C W

来源：Physical Review B, 2011, 83(9): 094517.

DOI：10.1103/PhysRevB.83.094517

The effects of the possible phase separation on macroscopic transport properties are explored in (Sr, K)Fe2As2. Three probes, the low-field shielding 4 pi(xZFC), the reversible diamagnetization M-SC at 5 T, and the specific heat C-p, with different characteristic length scales on the order of 10(3), 10, and 10(0) nm, respectively, were used to examine several (Sr1-xKx)Fe2As2 samples. The data from different probes should be consistent if the sample can be regarded as mesoscopically homogeneous. While this seems to be the case for the optimally doped x = 0.45 samples, the apparent transition temperature and the effective superfluid density strongly depend on the probes used for both the underdoped (x = 0.3) and the overdoped (x = 0.7) samples. Discrepancies of up to a factor of 10 are observed. The data further suggest that both the x = 0.3 and x = 0.7 samples are better described as Josephson-junction arrays formed over separated superconductive domains of 10-10(2) nm sizes. Such a morphology evolution may drastically affect the interpretation of the observed doping effects.

• 出版日期2011-3-14