New Insights on the Intrinsic Anisotropy of YBCO Films |
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Authors: | Mohammad Al-Naafa |
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Affiliation: | (1) Institute of Metallurgy UrD RAS, Ekaterinburg, 620016, Russia; |
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Abstract: | Careful investigation of the angular dependence of resistivity ρ(θ) (θ is the angle between the magnetic field and the ab-planes) and the temperature dependence of resistivity ρ(T) within the superconducting transition in an applied magnetic field B up to 1 T for a series of YBa2Cu3O7−δ
(YBCO) thin films revealed a large variation of intrinsic anisotropy factor γ. The series of films studied included both optimally doped and underdoped samples of different T
c
, critical current density J
c
, film thickness, and preparation techniques. The variation in the shape and depth of the minimum measured for ρ(θ) near θ=0° could be directly correlated to the intrinsic anisotropy of the YBCO films. The results of fitting of ρ(θ) using Bardeen–Stephen theory allowed a quantitative determination of the value of γ which varies between 7 and 230, and is independent of T
c
, film thickness, or J
c
. The sharper the minimum in ρ(θ) around θ=0° the larger is the anisotropy. For highly anisotropic film, ρ(θ) showed an identical behavior for B
∥
J and B
⊥
J (i.e., ρ(θ) is independent of the angle θ between B and J for this film). The large variation in γ could be attributed to the “buckling” of the CuO2 planes. |
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Keywords: | |
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