Interplane Resistivity of Underdoped Single Crystals (Ba₁₋ₓKₓ)Fe₂As₂ (0 ≤ x < 0.34)


The temperature-dependent interplane resistivity ρc(T) was measured in the hole-doped iron arsenide superconductor (Ba1-xKx)Fe2As2 over a doping range from parent compound to optimal doping at Tc ≈ 38 K, 0 ≤ x ≤ 0.34. The measurements were undertaken on high-quality single crystals grown from FeAs flux. The coupled magnetic/structural transition at TSM leads to a clear accelerated decrease of ρc(T) on cooling in samples with Tc < 26 K (x < 0.25). This decrease in the hole-doped material is in notable contrast to the increase in ρc(T) in the electron-doped Ba(Fe1-xCox)Fe2As2 and isoelectron-substituted BaFe2(As1-xPx)2. TSM decreases very sharply with doping, dropping from Ts = 71 K to zero on increase of Tc from approximately 25 to 27 K. ρc(T) becomes linear in T close to optimal doping. The broad crossover maximum in ρc(T), found in the parent BaFe2As2 at around Tmax ∼ 200 K, shifts to higher temperature ∼250 K with doping of x = 0.34. The maximum shows clear correlation with the broad crossover feature found in the temperature-dependent in-plane resistivity ρa(T). The evolution with doping of Tmax in (Ba1-xKx)Fe2As2 is in notable contrast with both the rapid suppression of Tmax found in Ba(Fe1-xTx)2As2 (T = Co,Rh,Ni,Pd) and its rapid increase in BaFe2(As1-xPx)2. This observation suggests that pseudogap features are much stronger in hole-doped than in electron-doped iron-based superconductors, revealing significant electron-hole doping asymmetry similar to that in the cuprates.




U.S. Department of Energy, Grant None

International Standard Serial Number (ISSN)

1550-235X; 1098-0121

Document Type

Article - Journal

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© 2014 American Physical Society (APS), All rights reserved.

Publication Date

30 Apr 2014