10,104 research outputs found
The observation of a positive magnetoresistance and close correlation among lattice, spin and charge around TC in antipervoskite SnCMn3
The temperature dependences of magnetization, electrical transport, and
thermal transport properties of antiperovskite compound SnCMn3 have been
investigated systematically. A positive magnetoresistance (~11%) is observed
around the ferrimagnetic-paramagnetic transition (TC ~ 280 K) in the field of
50 kOe, which can be attributed to the field-induced magnetic phase transition.
The abnormalities of resistivity, Seebeck coefficient, normal Hall effect and
thermal conductivity near TC are suggested to be associated with an abrupt
reconstruction of electronic structure. Further, our results indicate an
essential interaction among lattice, spin and charge degrees of freedom around
TC. Such an interaction among various degrees of freedom associated with sudden
phase transition is suggested to be characteristic of Mn-based antiperovskite
compounds.Comment: 13 pages, 5 figure
Twist-3 Contributions in Semi-Inclusive DIS in the Target Fragmentation Region
We present the complete results up to twist-3 for hadron production in the
target fragmentation region of semi-inclusive deep inelastic scattering with a
polarized lepton beam and polarized nucleon target. The non-perturbative
effects are factorized into fracture functions. The calculation up to twist-3
is non-trivial since one has to keep gauge invariance. By applying collinear
expansion, we show that the hadronic tensor can be expressed by gauge-invariant
fracture functions. We also present the results for the structure functions and
azimuthal asymmetries.Comment: 11 pages, 2 figure
Wave equation-based reflection tomography of the 1992 Landers earthquake area
In the framework of a recent wave equation-based traveltime seismic tomography, we show that incorporating Moho-reflected phases (PmP and SmS) in addition to the direct P and S phases can significantly increase tomography resolution in the lower crust and this may provide additional evidence to resolve important tectonic issues. To highlight the resolving power of the new strategy, we apply it in the region around the 1992 Landers earthquake (Mw = 7.3) in Southern California using seismic arrivals from local earthquakes, obtaining 3-D high-resolution P and S wave crustal velocity models and Poisson''s ratio structures. In the upper crust, our method confirmed features that had been previously found. However, in the middle-to-lower crust, we found low-velocity anomalies on the southeastern section of the San Jacinto Fault and high Vp and low Vs structures to the west of the Big Bear earthquake, which may be related to upwelling of partial melt from the mantle
Attosecond probing of instantaneous AC Stark shifts in helium atoms
Based on numerical solutions of the time-dependent Schr\"odinger equation for
either one or two active electrons, we propose a method for observing
instantaneous level shifts in an oscillating strong infrared (IR) field in
time, using a single tunable attosecond pulse to probe excited states of the
perturbed atom. The ionization probability in the combined fields depends on
both, the frequency of the attosecond pulse and the time delay between both
pulses, since the IR field shifts excited energy levels into and out of
resonance with the attosecond probe pulse. We show that this method (i) allows
the detection of instantaneous atomic energy gaps with sub-laser-cycle time
resolution and (ii) can be applied as an ultrafast gate for more complex
processes such as non-sequential double-ionization
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