Ames Laboratory, Physics and Astronomy
Physics and Astronomy, Ames Laboratory
Journal of Physics: Condensed Matter
Doping evolution of the superconducting gap anisotropy was studied in single crystals of 4d-electron doped Ba(Fe1-xRhx)(2)As-2 using tunnel diode resonator measurements of the temperature variation of the London penetration depth Delta lambda(T). Single crystals with doping levels representative of an underdoped regime x = 0.039 (T-c = 15.5 K), close to optimal doping x = 0.057 (T-c = 24.4 K) and overdoped x = 0.079 (T-c = 21.5 K) and x = 0.131 (T-c = 4.9 K) were studied. Superconducting energy gap anisotropy was characterized by the exponent, n, by fitting the data to the power-law, Delta lambda = AT(n). The exponent n varies non-monotonically with x, increasing to a maximum n = 2.5 for x = 0.079 and rapidly decreasing towards overdoped compositions to 1.6 for x = 0.131. This behavior is qualitatively similar to the doping evolution of the superconducting gap anisotropy in other iron pnictides, including hole-doped (Ba,K) Fe2As2 and 3d-electron-doped Ba(Fe,Co)(2)As-2 superconductors, finding a full gap near optimal doping and strong anisotropy toward the ends of the superconducting dome in the T-x phase diagram. The normalized superfluid density in an optimally Rh-doped sample is almost identical to the temperature-dependence in the optimally doped Ba(Fe,Co)(2)As-2 samples. Our study supports the universal superconducting gap variation with doping and s(+/-) pairing at least in iron based superconductors of the BaFe2As2 family.
Department of Energy Subject Categories
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Iowa State University Digital Repository, Ames IA (United States)
Available for download on Thursday, June 06, 2019