**Физика Низких Температур: ***Том ***43**, Выпуск **10** (Октябрь 2017), c. 1471-1481
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### How does the break-junction quasiparticle tunnel conductance look like for *d*-wave superconductors?

**Alexander M. Gabovich and Alexander I. Voitenko**

Institute of Physics, National Academy of Sciences of Ukraine, 46 Nauki Ave., Kyiv 03680, Ukraine

E-mail: gabovich@iop.kiev.ua, voitenko@iop.kiev.ua

*Received February 28, 2017*

**Аннотация**

The bias-voltage, *V*, dependences of the differential tunnel conductance *G*(*V*) = *dJ*/*DV* were calculated for the quasiparticle current *J* flowing in the *ab* plane across the break junction made of *d*-wave superconductors. The tunnel directionality effect was taken into account by introducing an effective tunneling cone described by the angle 2θ_{0}. It was shown that *G*(*V*) looks like predominantly *d*-wave or isotropic *s*-wave ones, depending on the magnitude of θ_{0} and the rotation angles of the crystal lattices of electrodes with respect to the junction plane. In certain configurations, the *G*(*V*) dependences of nominally symmetric S–I–S junctions may turn out similar to those for non-symmetric S–I–N junctions (here, S, I, and N denote superconductors, insulators, and normal metals, respectively) and provide misleading information about the actual energy gap. At finite temperatures, sub-gap structures appear, which possess features appropriate to both *d*- and *s*-wave superconductors and are dependent on the problem parameters.

PACS: 74.20.Rp Pairing symmetries (other than s-wave);

PACS: 74.55.+v Tunneling phenomena: single particle tunneling and STM;

PACS: 74.72.–h Cuprate superconductors.

**Ключевые слова: ***d*-wave superconductivity, quasiparticle tunnel conductivity, tunnel directionality, break junctions, high-*T*_{c} superconductors.

**Published online:** *August 27, 2017*