1,372 research outputs found
Magnetic-field-induced Stoner transition in a dilute quantum Hall system
In a recent paper [Phys.Rev.B.\textbf{84}, 161307 (2011)], experimental data
on spin splitting in the integer quantum Hall effect has been reported in a
high mobility dilute 2D electron gas with electron density as low as 0.2
10 cm . In this work, we show that an excellent
\emph{quantitative} description of these data can be obtained within the model
of the magnetic-field-induced Stoner transition in the quantum Hall regime.
This provides a powerful tool to probe the non-trivial density dependance of
electron-electron interactions in the dilute regime of the 2D electron gas
Quasiparticle density of states in BiSrCaCuO single crystals probed using tunneling spectroscopy at ultra-low temperatures in high magnetic fields
Break-junction tunneling spectroscopy at temperatures 30-50 mK in high
magnetic field is used to directly probe the quasiparticle density of states
within the energy gap in a single crystal Bi2212 high- superconductor. The
measured tunneling conductances in the subgap region have a zero
flat region with no evidence for a linear increase of the density of states
with voltage. A number of tunnel break-junctions exhibited curves
with a second energy gap structure at the average magnitude 2 mV. Our data cannot be explained by either a pure pairing or a
pure pairing
The performance document: assimilations of gesture and genre
Artist or activist actions and performances often take place just once and are intended to be experienced live. These actions are recorded and disseminated through photography and video taken from a range of perspectives, from paid-up and pre-briefed âprofessionalâ photographers or videographers through to spontaneously taken images by audience members or passers-by. Inevitably âdocumentationâ is never neutral and these records are infused with the stylistic intervention and conventions of the photographer in question. Within our conversation, we locate the performance document as the site of a potential two-way assimilation of gesture and stylistic attributes of diverse photographic conventions. In our co-writing, we track parallel analyses of photographs taken by commercial photographer Françoise Masson of the 1970s actions of artist Gina Pane and the utilization of photographs within the contemporary lens-based practice of Dinu Li, in which gesture and conventions are assimilated and move fluidly backwards and forwards between political propaganda, film, documentary, and domestic photography
Interplay among spin, orbital effects and localization in a GaAs two-dimensional electron gas in a strong in-plane magnetic field
The magnetoresistance of a low carrier density, disordered GaAs based
two-dimensional (2D) electron gas has been measured in parallel magnetic fields
up to 32 T. The feature in the resistance associated with the complete spin
polarization of the carriers shifts down by more than 20 T as the electron
density is reduced, consistent with recent theories taking into account the
enhancement of the electron-electron interactions at low densities.
Nevertheless, the magnetic field for complete polarization, Bp, remains 2-3
times smaller than predicted for a disorder free system. We show, in particular
by studying the temperature dependance of Bp to probe the effective size of the
Fermi sea, that localization plays an important role in determining the spin
polarization of a 2D electron gas.Comment: Published in the Physical Review
A consistent interpretation of the low temperature magneto-transport in graphite using the Slonczewski--Weiss--McClure 3D band structure calculations
Magnetotransport of natural graphite and highly oriented pyrolytic graphite
(HOPG) has been measured at mK temperatures. Quantum oscillations for both
electron and hole carriers are observed with orbital angular momentum quantum
number up to . A remarkable agreement is obtained when comparing
the data and the predictions of the Slonczewski--Weiss--McClure tight binding
model for massive fermions. No evidence for Dirac fermions is observed in the
transport data which is dominated by the crossing of the Landau bands at the
Fermi level, corresponding to , which occurs away from the point
where Dirac fermions are expected.Comment: 3 figure
Using the de Haas-van Alphen effect to map out the closed three-dimensional Fermi surface of natural graphite
The Fermi surface of graphite has been mapped out using de Haas van Alphen
(dHvA) measurements at low temperature with in-situ rotation. For tilt angles
between the magnetic field and the c-axis, the majority
electron and hole dHvA periods no longer follow the behavior
demonstrating that graphite has a 3 dimensional closed Fermi surface. The Fermi
surface of graphite is accurately described by highly elongated ellipsoids. A
comparison with the calculated Fermi surface suggests that the SWM trigonal
warping parameter is significantly larger than previously thought
Dirac fermions at the H point of graphite: Magneto-transmission studies
We report on far infrared magneto-transmission measurements on a thin
graphite sample prepared by exfoliation of highly oriented pyrolytic graphite.
In magnetic field, absorption lines exhibiting a blue-shift proportional to
sqrtB are observed. This is a fingerprint for massless Dirac holes at the H
point in bulk graphite. The Fermi velocity is found to be c*=1.02x10^6 m/s and
the pseudogap at the H point is estimated to be below 10 meV. Although the
holes behave to a first approximation as a strictly 2D gas of Dirac fermions,
the full 3D band structure has to be taken into account to explain all the
observed spectral features.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Let
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