Tal Kirzhner

Long-range proximity effect in La2/3Ca1/3MnO3/(100)YBa2Cu3O7−δferromagnet/superconductor bilayers: Evidence for induced triplet superconductivity in the ferromagnet

Scanning tunneling spectroscopy measurements conducted on epitaxially grown bilayers of half-metallic ferromagnetic La2/3Ca1/3MnO3 (LCMO) on superconducting (SC) (100)YBa2Cu3O7-delta (YBCO) reveal long-range penetration of superconducting order into the LCMO. This anomalous proximity effect manifests itself in the tunneling spectra measured on the LCMO layer as gaps and zero bias conductance peaks. Remarkably, these proximity-induced spectral features were observed for bilayers with LCMO thickness of up to 30 nm, an order of magnitude larger than the expected ferromagnetic coherence length in LCMO. We argue that this long-range proximity effect can be accounted for by the formation of spin triplet pairing at the LCMO side of the bilayer due to magnetic inhomogeneity at the interface or at domain walls. Possible symmetries of the induced order parameter are discussed.

Signature of proximity-induced px + ipy triplet pairing in the doped topological insulator Bi2Se3 by the s-wave superconductor NbN

In the search for Majorana fermions in proximity-induced topological superconducting junctions, we happened to find a signature of same-spin triplet superconductivity which appears to dominate these elusive elementary excitations. Thin-film junctions and bilayers of the doped topological insulator and the s-wave superconductor NbN exhibit conductance spectra with coexisting prominent zero-bias and coherence peaks. Various tunneling models with different pair potentials have failed to fit our data, except for the triplet pair potential, which breaks time-reversal symmetry, that yielded reasonably good fits. This provides supporting evidence for proximity-induced triplet superconductivity in the layer near the interface with the NbN film.

Zero-energy bound states in tunneling conductance spectra at the interface of ans-wave superconductor and a topological insulator in NbN/Bi2Se3/Au thin-film junctions

Measurements of conductance spectra in a superconductor - topological insulator - normal metal thin film junctions of NbN-

Pairing and the phase diagram of the normal coherence length ξN(T, x) above Tc of La(2-x)Sr(x)CuO4 thin films probed by the Josephson effect.

\rm Bi_2Se_3

Observation of two Andreev-like energy scales in La2-xSrxCuO4 superconductor-normal-metal-superconductor junctions.

-Au are reported. Junctions with ex-situ and in-situ prepared

Transport and spectroscopic properties of superconductor/ferromagnet/superconductor junctions of La1.9Sr0.1CuO4/La0.67Ca0.33MnO3/La1.9Sr0.1CuO4

\rm NbN-Bi_2Se_3

Magnetic field dependence of the proximity induced triplet superconductivity at ferromagnet/superconductor interfaces

interfaces were studied. At low temperatures, all the ex-situ junctions showed coherence peaks in their conductance spectra, but imbedded robust zero bias conductance peaks were observed only in junctions with a metallic or a metal to insulator transition below

Critical current measurements in superconductor-ferromagnet-superconductor junctions of YBa2Cu3Oy-SrRuO3-YBa2Cu3Oy: No evidence for dominant proximity-induced triplet superconductivity in the ferromagnetic barrier

\rm T_c

Optical studies of symmetry breaking in cuprate superconductors

of the NbN electrode. The in-situ junctions which had about two orders of magnitude lower resistance at low temperatures, generally showed flat conductance spectra at low bias, with no coherence or broad Andreev peaks, since the critical current of the NbN electrode was reached first, at voltage bias below the energy gap of the superconductor. A weak zero bias conductance peak however, was observed in one of these junctions. We conclude that significant tunneling barriers, as in the ex-situ prepared junctions, are essential for the observation of coherence peaks and the zero energy bound states. The later seem to originate in the

Infrared optical studies of symmetry breaking in cuprate superconductors over a wide doping range

\rm Bi_2Se_3