Physical Review Letters

Anisotropic rescaling of a splayed pinning landscape in hg cuprates: Strong vortex pinning and recovery of variable range hopping

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Strong vortex pinning by fission-induced uniformly splayed columnar tracks in anisotropic mercury cuprates is demonstrated to result from (re)scaling of the pinning landscape by a large superconducting anisotropy. The effective “narrowing” of the splay distribution restores variable range vortex hopping (VRH) motion expected for nearly parallel pins. VRH emerges as a distinctive peak in the vortex creep rate (∼12% at low fields at T/Tc ∼ 0.5) of the most anisotropic HgBa2 Ca2 Cu3 O8 + δ, a peak well described by a glassy dynamics with the characteristic exponent μ ∼ 1/3. © 1998 American Physical Society.