382 research outputs found
Chirality induced anomalous-Hall effect in helical spin crystals
Under pressure, the itinerant helimagnet MnSi displays unusual magnetic
properties. We have previously discussed a BCC helical spin crystal as a
promising starting point for describing the high pressure phenomenology. This
state has topologically nontrivial configurations of the magnetization field.
Here we note the consequences for magneto-transport that arise generally from
such spin textures. In particular a skyrmion density induced `topological' Hall
effect, with unusual field dependence, is described.Comment: 4 pages, 3 figures, to appear in the proceedings of SCES 07 (the
international conference on strongly correlated electron systems 2007 in
Houston, USA
Coherent electrical readout of defect spins in 4H-SiC by photo-ionization at ambient conditions
Quantum technology relies on proper hardware, enabling coherent quantum state
control as well as efficient quantum state readout. In this regard,
wide-bandgap semiconductors are an emerging material platform with scalable
wafer fabrication methods, hosting several promising spin-active point defects.
Conventional readout protocols for such defect spins rely on fluorescence
detection and are limited by a low photon collection efficiency. Here, we
demonstrate a photo-electrical detection technique for electron spins of
silicon vacancy ensembles in the 4H polytype of silicon carbide (SiC). Further,
we show coherent spin state control, proving that this electrical readout
technique enables detection of coherent spin motion. Our readout works at
ambient conditions, while other electrical readout approaches are often limited
to low temperatures or high magnetic fields. Considering the excellent maturity
of SiC electronics with the outstanding coherence properties of SiC defects the
approach presented here holds promises for scalability of future SiC quantum
devices
Loop-gap Microwave Resonator for Hybrid Quantum Systems
We designed a loop-gap microwave resonator for applications of spin-based
hybrid quantum systems, and tested it with impurity spins in diamond. Strong
coupling with ensembles of nitrogen-vacancy (NV) centers and substitutional
nitrogen (P1) centers was observed. These results show that loop-gap resonators
are viable in the prospect of spin-based hybrid quantum systems, especially for
an ensemble quantum memory or a quantum transducer.Comment: 5 pages, 4 figure
Robustness of the van Hove scenario for high-Tc superconductors
The pinning of the Fermi level to the van Hove singularity and the formation
of flat bands in the two-dimensional t-t' Hubbard model is investigated by the
renormalization group technique. The "van-Hove" scenario of non-Fermi-liquid
behavior for high-Tc compounds can take place in a broad enough range of the
hole concentrations. The results are in qualitative agreement with the recent
ARPES data on La2CuO4.Comment: 4 pages, LaTeX, 3 figure
Dorsal scapular artery as a recipient vessel in the vessel‐depleted neck during free tissue transfer in head and neck reconstruction
BackgroundThe vessel‐depleted neck poses a unique challenge to the microvascular surgeon. Using 3D modeling and cadaveric dissection, we describe the approach and advantages of a known but less frequently used recipient vessel, the dorsal scapular artery, during free tissue transfer.MethodsThree patients with vessel‐depleted necks required reconstruction with free tissue transfer. The dorsal scapular artery was used as a recipient vessel. Three‐dimensional anatomic models were created and cadaveric dissections were performed to characterize the anatomy.ResultsThe dorsal scapular artery was successfully used in 3 patients as the recipient pedicle for free tissue transfer. The vessel was identified deep in the posterior triangle after emerging through the brachial plexus. In all cases, the artery was in a previously undissected field, and had a large caliber and favorable geometry for microvascular anastomosis.ConclusionThe dorsal scapular artery is a viable recipient vessel during head and neck reconstruction in the vessel‐depleted neck.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137262/1/hed24785_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137262/2/hed24785.pd
Excitation spectrum and effective mass of the even-fraction quantum Hall liquid
To probe the nature of the even-fraction quantum Hall system, we have
investigated the low-lying excitation spectrum by means of exact
diagonalization for finite systems. We have found (i) a striking one-to-one
correspondence (i.e., a shell structure) between the spectrum and those for
free (composite) fermions, (ii) a surprisingly straight scaling plot for the
excitation energy that gives a zero gap (metal) in the thermodynamic limit,
(iii) the effective mass evaluated from the scaling becoming heavier for
filling factor = 1/2, 1/4, 1/6, but (iv) some deviations from the single-mode
or the Hartree-Fock composite fermion approximation as well.Comment: 4 pages, REVTeX format, 4 eps-figure
Mott Transition, Compressibility Divergence and P-T Phase Diagram of Layered Organic Superconductors: An Ultrasonic Investigation
The phase diagram of the organic superconductor
-(BEDT-TTF)Cu[N(CN)Cl has been investigated by ultrasonic
velocity measurements under helium gas pressure. Different phase transitions
were identified trough several elastic anomalies characterized from isobaric
and isothermal sweeps. Our data reveal two crossover lines that end on the
critical point terminating the first-order Mott transition line. When the
critical point is approached along these lines, we observe a dramatic softening
of the velocity which is consistent with a diverging compressibility of the
electronic degrees of freedom.Comment: 4 pages, 5 figure
Spin polarization separation of reflected light at Brewster angle
A novel spin polarization separation of reflected light is observed, when a
linearly polarized Gaussian beam impinges on an air-glass interface at Brewster
angle. In the far-field zone, spins of photons are oppositely polarized in two
regions along the direction perpendicular to incident plane. Spatial scale of
this polarization is related to optical properties of dielectric and can be
controlled by experimental configuration. We believe that this study benefits
the manipulation of spins of photons and the development of methods for
investigating optical properties of materials.Comment: 4 pages, 2 figure
Variation of polarization distribution of reflected beam caused by spin separation
The variation of polarization distribution of reflected beam at specular
interface and far field caused by spin separation has been studied. Due to the
diffraction effect, we find a distinct difference of light polarization at the
two regions. The variation of polarization distribution of reflected light
provides a new method to measure the spin separation displacement caused by
Spin Hall Effect of light.Comment: 7 pages, 5 figure
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