80,644 research outputs found
Selective Equal-Spin Andreev Reflections Induced by Majorana Fermions
In this work, we find that Majorana fermions induce selective equal spin
Andreev reflections (SESARs), in which incoming electrons with certain spin
polarization in the lead are reflected as counter propagating holes with the
same spin. The spin polarization direction of the electrons of this Andreev
reflected channel is selected by the Majorana fermions. Moreover, electrons
with opposite spin polarization are always reflected as electrons with
unchanged spin. As a result, the charge current in the lead is spin-polarized.
Therefore, a topological superconductor which supports Majorana fermions can be
used as a novel device to create fully spin-polarized currents in paramagnetic
leads. We point out that SESARs can also be used to detect Majorana fermions in
topological superconductors.Comment: 5 pages, 3 figures. Comments are welcome. Title changed to match
published versio
(13)C NMR investigation of the superconductor MgCNi_3 up to 800K
We report (13)C NMR characterization of the new superconductor MgCNi_3 (He et
al., Nature (411), 54 (2001)). We found that both the uniform spin
susceptibility and the spin fluctuations show a strong enhancement with
decreasing temperature, and saturate below ~50K and ~20K respectively. The
nuclear spin-lattice relaxation rate 1/(13)T_1T exhibits typical behaviour for
isotropic s-wave superconductivity with a coherence peak below Tc=7.0K that
grows with decreasing magnetic field.Comment: Accepted for publication in Physical Review Letter
Heat Capacity of ^3He in Aerogel
The heat capacity of pure ^3He in low density aerogel is measured at 22.5
bar. The superfluid response is simultaneously monitored with a torsional
oscillator. A slightly rounded heat capacity peak, 65 mu K in width, is
observed at the ^3He-aerogel superfluid transition, T_{ca}. Subtracting the
bulk ^3He contribution, the heat capacity shows a Fermi-liquid form above
T_{ca}. The heat capacity attributed to superfluid within the aerogel can be
fit with a rounded BCS form, and accounts for 0.30 of the non-bulk fluid in the
aerogel, indicating a substantial reduction in the superfluid order parameter
consistent with earlier superfluid density measurements.Comment: 4 pages, 5 figure
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