Work

Interplane resistivity of underdoped single crystals (Ba 1−x K x )Fe 2 As 2 ( 0≤x<0.34 )

Year: 2014

Type: article

Abstract: The temperature-dependent interplane resistivity ${\ensuremath{\rho}}_{c}(T)$ was measured in the hole-doped iron arsenide superconductor (Ba${}_{1\ensuremath{-}x}$K${}_{x}$)Fe${}_{2}$As${}_{2}$ over a doping range from parent compound to optimal doping at ${T}_{c}\ensuremath{\approx}38$ K, $0\ensuremath{\le}x\ensuremath{\le}0.34$. The measurements were undertaken on high-quality single crystals grown from FeAs flux. The coupled magnetic/structural transition at ${T}_{SM}$ leads to a clear accelerated decrease of ${\ensuremath{\rho}}_{c}(T)$ on cooling in samples with ${T}_{c}<26$ K ($x<0.25$). This decrease in the hole-doped material is in notable contrast to the increase in ${\ensuremath{\rho}}_{c}(T)$ in the electron-doped Ba(Fe${}_{1\ensuremath{-}x}$Co${}_{x}$)Fe ${}_{2}$As${}_{2}$ and isoelectron-substituted BaFe${}_{2}$(As${}_{1\ensuremath{-}x}$P${}_{x}$)${}_{2}$. ${T}_{SM}$ decreases very sharply with doping, dropping from ${T}_{s}=71$ K to zero on increase of ${T}_{c}$ from approximately 25 to 27 K. ${\ensuremath{\rho}}_{c}(T)$ becomes linear in $T$ close to optimal doping. The broad crossover maximum in ${\ensuremath{\rho}}_{c}(T)$, found in the parent BaFe${}_{2}$As${}_{2}$ at around ${T}_{\mathrm{max}}\ensuremath{\sim}200$ K, shifts to higher temperature $\ensuremath{\sim}$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 ${\ensuremath{\rho}}_{a}(T)$. The evolution with doping of ${T}_{\mathrm{max}}$ in (Ba${}_{1\ensuremath{-}x}$K${}_{x}$)Fe${}_{2}$As${}_{2}$ is in notable contrast with both the rapid suppression of ${T}_{\mathrm{max}}$ found in Ba(Fe${}_{1\ensuremath{-}x}{T}_{x}$)${}_{2}$As${}_{2}$ ($T=\text{Co}$,Rh,Ni,Pd) and its rapid increase in BaFe${}_{2}$(As${}_{1\ensuremath{-}x}$P${}_{x}$)${}_{2}$. 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.

Source: Physical Review B

DOI: 10.1103/physrevb.89.144514