Field-controlled Dirac Fermions in the Vortex-Lattice Cores of quasi 2D Superconductor

When: Tuesday 10 Septembre, 12h30-13h30.
Where: Modulo 08 (Sala de grados módulo 08), 2nd floor, Facultad de Ciencias

Speaker: Tsofar Maniv, Technion

Abstract:
The “ideal” superconductivity of pure metals at low temperatures under high magnetic fields is currently not well understood even within the conventional BCS theory. Magnetic quantum oscillations have been observed in the mixed state of many strongly type-II  superconductors. Proper analysis of the experimental data is of crucial importance for fundamental understanding this “ideal” superconducting (SC) state. The dominant  effect of  the SC order parameter on magneto oscillations observed so far has been an extra damping to the usual thermal and disorder damping of the oscillatory signal, impeding effective analysis of the data.
Direct probe of the quasi particle density of states at high magnetic fields and low temperatures, e.g. by using STM-STS, could be very helpful in circumventing this shortcoming.
In this talk I will describe the underlying connections between characteristic features of the quasi-particle density of states and the resulting magneto-oscillation structures. Our analytical approach has recently revealed a new magneto-oscillations effect peculiar to the ordered vortex lattice state. The discovered effect is due to coherent Andreev scattering of quasi particles passing through many vortex core regions, which leads to “erratically” oscillating modulation of the magneto-oscillation amplitude.  We have also shown that in a quasi 2D superconductor the creation of Dirac cone structures of the Landau quantized quasi particle spectrum, associated with the topological singularity of the order parameter at the vortex lattice cores, is closely related to the discovered erratic oscillations effect