398 research outputs found
Fabrication of magnetic atom chips based on FePt
We describe the design and fabrication of novel all-magnetic atom chips for
use in ultracold atom trapping. The considerations leading to the choice of
nanocrystalline exchange coupled FePt as best material are discussed. Using
stray field calculations, we designed patterns that function as magnetic atom
traps. These patterns were realized by spark erosion of FePt foil and e-beam
lithography of FePt film. A mirror magneto-optical trap (MMOT) was obtained
using the stray field of the foil chip.Comment: 5 pages, 5 figure
A lattice of microtraps for ultracold atoms based on patterned magnetic films
We have realized a two dimensional permanent magnetic lattice of
Ioffe-Pritchard microtraps for ultracold atoms. The lattice is formed by a
single 300 nm magnetized layer of FePt, patterned using optical lithography.
Our magnetic lattice consists of more than 15000 tightly confining microtraps
with a density of 1250 traps/mm. Simple analytical approximations for the
magnetic fields produced by the lattice are used to derive relevant trap
parameters. We load ultracold atoms into at least 30 lattice sites at a
distance of approximately 10 m from the film surface. The present result
is an important first step towards quantum information processing with neutral
atoms in magnetic lattice potentials.Comment: 7 pages, 7 figure
Permutation entropy as a universal disorder criterion: how disorders at different scale levels are manifestations of the same underlying principle
Action Contro
Assessment of environmental performance of shaped tube electrolytic machining (STEM) and capillary drilling (CD) of superalloys
Nanoscale superconducting gap variations, strong coupling signatures and lack of phase separation in optimally doped BaFe1.86Co0.14As2
We present tunneling data from optimally-doped, superconducting
BaFe1.86Co0.14As2 and its parent compound, BaFe2As2. In the superconductor,
clear coherence-like peaks are seen across the whole field of view, and their
analysis reveals nanoscale variations in the superconducting gap value, Delta.
The average magnitude of 2Delta is ~7.4 kBTC, which exceeds the BCS weak
coupling value for either s- or d-wave superconductivity. The characteristic
length scales of the deviations from the average gap value, and of an
anti-correlation discovered between the gap magnitude and the zero bias
conductance, match well with the average separation between the Co dopant ions
in the superconducting FeAs planes. The tunneling spectra themselves possess a
peak-dip-hump lineshape, suggestive of a coupling of the superconducting
electronic system to a well-defined bosonic mode of energy 4.7 kBTC, such as
the spin resonance observed recently in inelastic neutron scattering.Comment: 4 figures, corrected typos, reduced size of image
Process level environmental performance of electrodischarge machining of aluminium (3003) and steel (AISI P20)
Creating Ioffe-Pritchard micro-traps from permanent magnetic film with in-plane magnetization
We present designs for Ioffe-Pritchard type magnetic traps using planar
patterns of hard magnetic material. Two samples with different pattern designs
were produced by spark erosion of 40 m thick FePt foil. The pattern on the
first sample yields calculated axial and radial trap frequencies of 51 Hz and
6.8 kHz, respectively. For the second sample the calculated frequencies are 34
Hz and 11 kHz. The structures were used successfully as a magneto-optical trap
for Rb and loaded as a magnetic trap. A third design, based on
lithographically patterned 250 nm thick FePt film on a Si substrate, yields an
array of 19 traps with calculated axial and radial trap frequencies of 1.5 kHz
and 110 kHz, respectively.Comment: 8 pages, 5 figures Revised and accepted for EPJD, improved picture
Spin-Resolved Photoemission on Anti-Ferromagnets: Direct Observation of Zhang-Rice Singlets in CuO
We demonstrate that it is possible to obtain spin-resolved valence band spectra with a very high
degree of spin polarization from antiferromagnetic transition metal materials if the excitation light is
circularly polarized and has an energy close to the cation 2p3/2 (L3) white line. We are able to unravel
the different spin states in the single-particle excitation spectrum of CuO and show that the top of the
valence band is of pure singlet character, which provides strong support for the existence and stability
of Zhang-Rice singlets in high-Tc superconductors
Local Electronic and Magnetic Structure of Ni below and above TC: A Spin-Resolved Circularly Polarized Resonant Photoemission Study
We report the measurement of the local Ni 3d spin polarization, not only below but also above the
Curie temperature (TC), using the newly developed spin-resolved circularly polarized 2p (L3) resonant
photoemission technique. The experiment identifies the presence of 3d8 singlets at high energies and
3d8 triplets at low energies extending all the way to the Fermi energy, both below and above TC,
showing that it is the orbital degeneracy of the 3d band and the Hund's rule splitting which is of utmost
importance to understand Ni and other 3d ferromagnets
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