162 research outputs found
A class of Calogero type reductions of free motion on a simple Lie group
The reductions of the free geodesic motion on a non-compact simple Lie group
G based on the symmetry given by left- and right
multiplications for a maximal compact subgroup are
investigated. At generic values of the momentum map this leads to (new) spin
Calogero type models. At some special values the `spin' degrees of freedom are
absent and we obtain the standard Sutherland model with three
independent coupling constants from SU(n+1,n) and from SU(n,n). This
generalization of the Olshanetsky-Perelomov derivation of the model with
two independent coupling constants from the geodesics on with
G=SU(n+1,n) relies on fixing the right-handed momentum to a non-zero character
of . The reductions considered permit further generalizations and work at
the quantized level, too, for non-compact as well as for compact G.Comment: shortened to 13 pages in v2 on request of Lett. Math. Phys. and
corrected some spelling error
Electron transport through antidot superlattices in heterostructures: new magnetoresistance resonances in lattices with large diameter antidots
In the present work we have investigated the transport properties in a number
of Si/SiGe samples with square antidot lattices of different periods. In
samples with lattice periods equal to 700 nm and 850 nm we have observed the
conventional low-field commensurability magnetoresistance peaks consistent with
the previous observations in GaAs/AlGaAs and Si/SiGe samples with antidot
lattices. In samples with a 600 nm lattice period a new series of
well-developed magnetoresistance oscillations has been found beyond the last
commensurability peak which are supposed to originate from periodic skipping
orbits encircling an antidot with a particular number of bounds.Comment: To appear in EuroPhys. Let
Transport properties of a 3D topological insulator based on a strained high mobility HgTe film
We investigated the magnetotransport properties of strained, 80nm thick HgTe
layers featuring a high mobility of mu =4x10^5 cm^2/Vs. By means of a top gate
the Fermi-energy is tuned from the valence band through the Dirac type surface
states into the conduction band. Magnetotransport measurements allow to
disentangle the different contributions of conduction band electrons, holes and
Dirac electrons to the conductivity. The results are are in line with previous
claims that strained HgTe is a topological insulator with a bulk gap of ~15meV
and gapless surface states.Comment: 11 pages (4 pages of main text, 6 pages of supplemental materials), 8
figure
Unconventional Hall effect near charge neutrality point in a two-dimensional electron-hole system
The transport properties of the two-dimensional system in HgTe-based quantum
wells containing simultaneously electrons and holes of low densities are
examined. The Hall resistance, as a function of perpendicular magnetic field,
reveals an unconventional behavior, different from the classical N-shaped
dependence typical for bipolar systems with electron-hole asymmetry. The
quantum features of magnetotransport are explained by means of numerical
calculation of the Landau level spectrum based on the Kane Hamiltonian. The
origin of the quantum Hall plateau {\sigma}xy = 0 near the charge neutrality
point is attributed to special features of Landau quantization in our system.Comment: 8 pages, 7 figure
On frequencies of small oscillations of some dynamical systems associated with root systems
In the paper by F. Calogero and author [Commun. Math. Phys. 59 (1978)
109-116] the formula for frequencies of small oscillations of the Sutherland
system ( case) was found. In present note the generalization of this
formula for the case of arbitrary root system is given.Comment: arxiv version is already officia
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