Normal-State Resistivity Anisotropy in UnderdopedRBa2Cu3O6+

Abstract

We have revealed new features in the out-of-plane resistivity ρc of heavily underdoped RBa2Cu3O6+x (R=Tm,Lu) single crystals, which give evidence for two distinct mechanisms contributing the c-axis transport. We have observed a crossover towards "metal-like" (∂ρc/∂T > 0) behavior at the temperature Tm which quickly increases with decreasing doping. The "metallike" conductivity contribution dominates at T < Tm and provides a saturation of the resistivity anisotropy, ρc/ρ ab . The antiferromagnetic ordering is found to block this "metal-like" part of the c-axis conductivity and complete decoupling of CuO2 planes, which may be the reason of superconductivity disappearance.

Magnetoresistance in Heavily UnderdopedYBa2Cu3O6Лавров1, Ando2, Segawa3 et al. 1999Phys. Rev. Lett.Self Cite396361View full textAdd to dashboardCite

“…The dynamic AF correlations developed in the CuO 2 planes evolve into the long-range AF order upon crossing the Néel temperature T N [1], and one can expect some singular behavior to show up in the properties governed by the the magnetic interactions. A magnetotransport study in the vicinity of T N is therefore an attractive possibility to clarify the role of spin degrees of freedom in the peculiar electron transport.In this Letter, we present a study of the in-plane and out-of-plane MR of heavily underdoped antiferromagnetic Y-123 crystals, supplemented by measurements of the Lu-123 crystal used earlier for the study of the phase diagram [9]. We find that the out-of-plane MR undergoes a drastic change in the vicinity of the Néel temperature, increasing by about two orders of magnitude with a transition into the AF state.…”

“…In this Letter, we present a study of the in-plane and out-of-plane MR of heavily underdoped antiferromagnetic Y-123 crystals, supplemented by measurements of the Lu-123 crystal used earlier for the study of the phase diagram [9]. We find that the out-of-plane MR undergoes a drastic change in the vicinity of the Néel temperature, increasing by about two orders of magnitude with a transition into the AF state.…”

“…The MR measurements are performed either by sweeping temperature (controlled by a Cernox resistance sensor) in constant magnetic fields up to 16 T, or by sweeping the field at a fixed temperature stabilized by a capacitance sensor to an accuracy of about 1 mK. The latter method allows measurements of ∆ρ/ρ as small as 10 −5 at 10 T. It was recently reported that heavily underdoped RBa 2 Cu 3 O 6+x (R=Tm, Lu) exhibits a maximum in ρ c (T ), which originates from a competition between two distinct mechanisms contributing to the interplane transport [9]. The long-range AF ordering brings about an additional peculiarity; an abrupt increase in ρ c occurs upon cooling through T N , which is followed by a resistivity di- vergence at lower T [9].…”

“…The latter method allows measurements of ∆ρ/ρ as small as 10 −5 at 10 T. It was recently reported that heavily underdoped RBa 2 Cu 3 O 6+x (R=Tm, Lu) exhibits a maximum in ρ c (T ), which originates from a competition between two distinct mechanisms contributing to the interplane transport [9]. The long-range AF ordering brings about an additional peculiarity; an abrupt increase in ρ c occurs upon cooling through T N , which is followed by a resistivity di- vergence at lower T [9]. We confirm essentially the same behavior in YBa 2 Cu 3 O 6+x , and in Fig.…”

Magnetotransport study of the charged stripes in high-T cuprates

“…The heavily-underdoped YBCO crystals, though located deep in the AF range of the phase diagram (x≈0.3), are far from conventional insulators: the in-plane resistivity ρ ab remains "metallic" at high T and it grows slower than expected for the hopping electron transport at low T [8,9]. These AF crystals demonstrate an unusual behavior of the in-plane MR, ∆ρ ab /ρ ab , when the magnetic field H is applied along the CuO 2 planes, as shown in Fig.…”