274 research outputs found
Measurement of the spatial extent of inverse proximity in a Py/Nb/Py superconducting trilayer using low-energy muon-spin rotation
The authors acknowledge the financial support of the EPSRC (Grant No. EP/J01060X).Muon-spin rotation has been used to observe directly the spatial variation of the magnetic flux density near the ferromagnetic-superconducting interface in a permalloy-niobium trilayer. Above the superconducting transition temperature Tc the profile of the induced magnetic flux density within the niobium layer has been determined. Below Tc there is a significant reduction of the induced flux density, predominantly near the ferromagnetic-superconducting interfaces. We are uniquely able to determine the magnitude and spatial variation of this reduction in induced magnetization due to the presence of the Cooper pairs, yielding the magnitude and length scale associated with this phenomenon. Both are inconsistent with a simple Meissner screening and indicate the existence of another mechanism, the influence of which is localized within the vicinity of the ferromagnetic interface.Publisher PDFPeer reviewe
Avoided ferromagnetic quantum critical point: Unusual short-range ordered state in CeFePO
Cerium 4f electronic spin dynamics in single crystals of the heavy-fermion
system CeFePO is studied by means of ac-susceptibility, specific heat and
muon-spin relaxation (SR). Short-range static magnetism occurs below the
freezing temperature Tg ~ 0.7 K, which prevents the system from accessing the
putative ferromagnetic quantum critical point. In the SR, the
sample-averaged muon asymmetry function is dominated by strongly inhomogeneous
spin fluctuations below 10 K and exhibits a characteristic time-field scaling
relation expected from glassy spin dynamics, strongly evidencing cooperative
and critical spin fluctuations. The overall behavior can be ascribed neither to
canonical spin glasses nor other disorder-driven mechanisms.Comment: 5 pages, 4 figures, accepted for publication in Physical Review
Letters, Link:
http://prl.aps.org/accepted/6207bYdaGef1483c419928305372ce2d4419eb96
Extended Magnetic Dome Induced by Low Pressures in Superconducting FeSeS
We report muon spin rotation (SR) and magnetization measurements under
pressure on FeSeS with x
.Above GPa we find microscopic coexistence of
superconductivity with an extended dome of long range magnetic order that spans
a pressure range between previously reported separated magnetic phases. The
magnetism initially competes on an atomic scale with the coexisting
superconductivity leading to a local maximum and minimum of the superconducting
. The maximum of corresponds to the onset of
magnetism while the minimum coincides with the pressure of strongest
competition. A shift of the maximum of for a series of single
crystals with x up to 0.14 roughly extrapolates to a putative magnetic and
superconducting state at ambient pressure for x .Comment: 10 pages, 6 figures, including supplemental materia
Direct observation of non-local effects in a superconductor
We have used the technique of low energy muon spin rotation to measure the
local magnetic field profile B(z) beneath the surface of a lead film maintained
in the Meissner state (z depth from the surface, z <= 200 nm). The data
unambiguously show that B(z) clearly deviates from an exponential law and
represent the first direct, model independent proof for a non-local response in
a superconductor.Comment: 5 pages, 3 figure
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