arXiv subjects

Y. Hu

Publications and source records attributed to Y. Hu.

113 records · Page 7Linked to original sources

arXiv2008

Spin-orbit interaction effect in the electronic structure of \BiTe \ observed by angle-resolved photoemission spectroscopy

The electronic structure of $p$-type doped \BiTe is studied by angle resolved photoemission spectroscopy (ARPES) to experimentally confirm the mechanism responsible for the high thermoelectric figure of merit. Our ARPES study shows that the band edges are located off the $Γ$-Z line in the Brillouin zone, which provides direct observation that the spin-orbit interaction is a key factor to understand the electronic structure and the corresponding thermoelectric properties of \BiTe. Successive time dependent ARPES measurement also reveals that the electron-like bands crossing E$_F$ near the $\underlineΓ$ point are formed in an hour after cleaving the crystals. We interpret these as surface states induced by surface band bending, possibly due to quintuple inter-layer distance change of \BiTe.

cond-mat.mtrl-sci↗

arXiv2007

Plasma effects in a micromachined floating-gate high-electron-mobility transistor

We study plasma effects in a micromachined high-electron mobility transistor (HEMT) with the microcantilever serving as the gate using the developed a model. The model accounts for mechanical motion of the microcantilever and spatio-temporal variations (plasma effects) of the two-dimensional electron gas(2DEG) system in the transistor channel. The microcantilever mechanical motion is described in the point-mass approximation. The hydrodynamic electron transport model is used to describe distributed electron plasma phenomena in the 2DEG system. Using the developed model, we calculated the response function characterizing the amplitude microcantilever oscillations and the output electric signal as functions of the signal frequency and the bias voltage for the devices with different parameters. We find the voltage dependences of the frequency of the mechanical resonance and its damping. In particular, it is demonstrated that the amplitudes of the mechanical oscillations and output electric signal exhibit pronounced maxima at the bias voltages close to the voltage of the 2DEG channel depletion followed by a steep drop with further increase in the bias voltage.

cond-mat.mes-hall↗

arXiv2005

Enhanced flux pinning in YBa2Cu3O7-d films by nano-scaled substrate surface roughness

Nano-scaled substrate surface roughness is shown to strongly influence the critical current density Jc in YBCO films made by pulse-laser-deposition on the crystalline LaAlO3 substrates consisting of two separate twin-free and twin-rich regions. The nano-scaled corrugated surface was created in the twin-rich region during the deposition process. Using magneto-optical imaging techniques coupled with optical and atomic force microscopy, we observed an enhanced flux pinning in the YBCO films in the twin-rich region, resulted in \~30% increase in Jc, which was unambiguously confirmed by the direct transport measurement.

cond-mat.supr-con↗

arXiv2004

Ultra High Energy $ν_τ$ Detection Using Cosmic Ray Tau Neutrino Telescope Used in Fluorescence/Cerenkov Light Detection

We have investigated the possibility of $ν_τ$ detection using Cosmic Ray Tau Neutrino Telescope (CRTNT) based on air shower fluorescence/Cerenkov light detector techniques. This approach requires an interaction of a $ν_τ$ with material such as a mountain or the earth's crust. $τ$ lepton produced in the charged current interaction must escape from the earth and then decay and initiate a shower in the air. The probability for the conversion from $ν_τ$ to air shower has been calculated for an energy range from 1 PeV to 10 EeV. An air shower simulation program has been developed using the simulation package Corsika. The trigger efficiency has been estimated for a CRTNT detector similar to the HiRes/Dice detector in the shadow of Mt. Wheeler in Nevada, USA. A rate of about 8 triggered events per year is expected for the AGN neutrino source model with an optimized configuration and duty cycle of the detector.

astro-ph↗

arXiv2002

Tangent Processes on Wiener Space

This paper deals with the study of the Malliavin calculus of Euclidean motions on Wiener space, (i.e. transformations induced by general measure preserving transformations, called `rotations', and H-valued shifts) and the associated flows on abstract Wiener spaces

math.PR↗