Electronic vortex structure and flux-flow resistance steps in the cuprate superconductor ${\rm Nd}_{2-x}{\rm Ce}_x{\rm CuO}_y$

R.P. Huebener; S. Kaiser; O.M. Stoll

doi:doi:10.1209/epl/i1998-00540-7

DOI: 10.1209/epl/i1998-00540-7

Europhys. Lett, 44 (6), pp. 772-777 (1998)

Electronic vortex structure and flux-flow resistance steps
in the cuprate superconductor ${\rm Nd}_{2-x}{\rm Ce}_x{\rm CuO}_y$

R. P. Huebener, S. Kaiser and O. M. Stoll

Physikalisches Institut, Lehrstuhl Experimentalphysik II
Universität Tübingen, Morgenstelle 14 - D-72076 Tübingen, Germany

(received 2 September 1998; accepted 17 October 1998)

PACS. 74.25Fy - Transport properties (electric and thermal conductivity, thermoelectric effects, etc.).
PACS. 74.60Ge - Flux pinning, flux creep, and flux-line lattice dynamics.
PACS. 74.72Jt - Other cuprates.

Abstract:

For the superconducting mixed state in the clean limit the electronic density of states $N(\varepsilon)$ above and below the Fermi energy $\varepsilon = 0$ is given by the bound states in the vortex core, with the minigap $\varepsilon_0$ as a prominent feature. Quasiclassically, $N(\varepsilon)$ shows a steep increase near the energy gap $\Delta$ . Since $N(\varepsilon)$ provides the phase space for quasiparticle scattering, these features are expected to strongly affect the flux-flow resistance. Our recent observation of two intrinsic flux-flow resistance steps in epitaxial films of ${\rm Nd}_{2-x}{\rm Ce}_x{\rm CuO}_y$ are explained in terms of these features of $N(\varepsilon)$ near $\varepsilon=\varepsilon_0$ and $\varepsilon = \Delta$ , respectively. The instabilities resulting for current-bias from an electric-field-dependent resistance are discussed in general terms.

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