25,230 research outputs found
Critical current of a superconductor measured via injection of spin polarized carriers
In this paper we report a direct evidence of the suppression of critical
current due to pair-breaking in a superconducting micro-bridge when the
measurement is carried out by injecting spin polarised carriers instead of
normal electrons. A thin layer of La0.7Ca0.3MnO3 was used as the source of spin
polarised carriers. The micro-bridge was formed on the DyBa2Cu3O7-d thin film
by photo-lithographic techniques. The design of our spin-injection device
allowed us to inject spin-polarised carriers from the La0.7Ca0.3MnO3 layer
directly to the DyBa2Cu3O7- d micro-bridge (without any insulating buffer
layer) making it possible to measure the critical current when polarised
electrons alone are injected into the superconductor. Our results confirm the
role of polarised carriers in breaking the Cooper pairs in the superconductor.Comment: 8 pages, 4 figure
Unconventional magnetism in multivalent charge-ordered YbPtGe probed by Pt- and Yb-NMR
Detailed Pt- and Yb nuclear magnetic resonance (NMR) studies
on the heterogeneous mixed valence system YbPtGe are reported. The
temperature dependence of the Pt-NMR shift indicates the
opening of an unusual magnetic gap below 200\,K. was analyzed by a
thermal activation model which yields an isotropic gap \,K. In contrast, the spin-lattice relaxation rate () does
not provide evidence for the gap. Therefore, an intermediate-valence picture is
proposed while a Kondo-insulator scenario can be excluded. Moreover,
() follows a simple metallic behavior, similar to the reference
compound YPtGe. A well resolved NMR line with small shift is assigned to
divalent Yb. This finding supports the proposed model with two sub-sets
of Yb species (di- and trivalent) located on the Yb2 and Yb1 site of the
YbPtGe lattice.Comment: Submitted in Physical Review B (Rapid Communication
Character of Locally Inequivalent Classes of States and Entropy of Entanglement
In this letter we have established the physical character of pure bipartite
states with the same amount of entanglement in the same Schmidt rank that
either they are local unitarily connected or they are incomparable. There exist
infinite number of deterministically locally inequivalent classes of pure
bipartite states in the same Schmidt rank (starting from three) having same
amount of entanglement. Further, if there exists incomparable states with same
entanglement in higher Schmidt ranks (greater than three), then they should
differ in at least three Schmidt coefficients.Comment: 4 pages, revtex4, no figure, accepted in Physical Review A (rapid
communications
Spin rings in bi-stable planar semiconductor microcavities
A unique feature of exciton-polaritons, inherited from their mixed
light-matter origin, is the strongly spin-dependent polariton-polariton
interaction, which has been predicted to result in the formation of spin rings
in real space [Shelykh et al., Phys. Rev. Lett. 100, 116401 (2008)]. Here we
experimentally demonstrate the spin bi-stability of exciton-polaritons in an
InGaAs-based semiconductor microcavity under resonant optical pumping. We
observe the formation of spin rings whose size can be finely controlled in a
spatial scale down to the micrometer range, much smaller than the spot size. We
additionally evaluate the sign and magnitude of the antiparallel polariton spin
interaction constant.Comment: 5 pages, 4 figure
- …