31 research outputs found
Superconductivity and Ferromagnetism in Oxide Interface Structures: Possibility of Finite Momentum Pairing
We introduce a model to explain the observed ferromagnetism and
superconductivity in LAO/STO oxide interface structures. Due to the polar
catastrophe mechanism, 1/2 charge per unit cell is transferred to the interface
layer. We argue that this charge localizes and orders ferromagnetically via
exchange with the conduction electrons. Ordinarily this ferromagnetism would
destroy superconductivity, but due to strong spin-orbit coupling near the
interface, the magnetism and superconductivity can coexist by forming an
FFLO-type condensate of Cooper pairs at finite momentum, which is surprisingly
robust in the presence of strong disorder.Comment: 6 pages of Supplementary materials added containing details of
calculation and further discussion of the FFLO state with disorder,
references added, final version as publishe
Electron Teleportation in Multi-Terminal Majorana Islands: Statistical Transmutation and Fractional Quantum Conductance
We study a topological superconductor island with spatially separated
Majorana modes coupled to multiple normal metal leads by single electron
tunneling in the Coulomb blockade regime. We show that low-temperature
transport in such Majorana island is carried by an emergent charge- boson
composed of a Majorana mode and an electron from the leads. This transmutation
from Fermi to Bose statistics has remarkable consequences. For noninteracting
leads, the system flows to a non-Fermi liquid fixed point, which is stable
against tunnel couplings anisotropy or detuning away from the charge-degeneracy
point. As a result, the system exhibits a universal conductance at zero
temperature, which is a fraction of the conductance quantum, and
low-temperature corrections with a universal power-law exponent. In addition,
we consider Majorana islands connected to interacting one-dimensional leads,
and find different stable fixed points near and far from the charge-degeneracy
point.Comment: 10+ pages, 5 figure
Giant chirality-induced spin-selectivity of polarons
The chirality-induced spin selectivity (CISS) effect gives rise to strongly
spin-dependent transport through many organic molecules and structures. Its
discovery raises fascinating fundamental questions as well as the prospect of
possible applications. The basic phenomenology, a strongly asymmetric
magnetoresistance despite the absence of magnetism, is now understood to result
from the combination of spin-orbit coupling and chiral geometry. However,
experimental signatures of electronic helicity were observed at room
temperature, i.e., at an energy scale that exceeds the typical spin-orbit
coupling in organic systems by several orders of magnitude. This work shows
that a new energy scale for CISS emerges for currents carried by polarons,
i.e., in the presence of strong electron-phonon coupling. In particular, we
found that polaron fluctuations play a crucial role in the two manifestations
of CISS in transport measurements -- the spin-dependent transmission
probability through the system and asymmetric magnetoresistance
We Must Not Make a Scarecrow of the Law: A Legal Analysis of the Israeli Policy of Targeted Killings
We Must Not Make a Scarecrow of the Law: A Legal Analysis of the Israeli Policy of Targeted Killings
Revealing topological superconductivity in extended quantum spin Hall Josephson junctions
Quantum spin Hall–superconductor hybrids are promising sources of topological superconductivity and Majorana modes, particularly given recent progress on HgTe and InAs/GaSb. We propose a new method of revealing topological superconductivity in extended quantum spin Hall Josephson junctions supporting “fractional Josephson currents.” Specifically, we show that as one threads magnetic flux between the superconductors, the critical current traces an interference pattern featuring sharp fingerprints of topological superconductivity—even when noise spoils parity conservation