2,140 research outputs found
Quantum integrability of the deformed elliptic Calogero-Moser problem
The integrability of the deformed quantum elliptic Calogero-Moser problem
introduced by Chalykh, Feigin and Veselov is proven. Explicit recursive
formulae for the integrals are found. For integer values of the parameter this
implies the algebraic integrability of the systems.Comment: 23 page
Fermi Surface Study of Quasi-Two-Dimensional Organic Conductors by Magnetooptical Measurements
Magnetooptical measurements of several quasi-two-dimensional (q2D) organic
conductors, which have simple Fermi surface structure, have been performed by
using a cavity perturbation technique. Despite of the simple Fermi surface
structure, magnetooptical resonance results show a dramatic difference for each
sample. Cyclotron resonances (CR) were observed for q-(BEDT-TTF)2I3 and
(BEDT-TTF)3Br(pBIB), while periodic orbit resonances (POR) were observed for
(BEDT-TTF)2Br(DIA) and (BEDT-TTF)3Cl(DFBIB). The selection of the resonance
seems to correspond with the skin depth for each sample. The effective mass of
POR seems to have a mass enhancement due to the many-body effect, while
effective mass of CR is independent of the strength of the electron-electron
interaction. The scattering time deduced from each resonance's linewidth will
be also presented.Comment: 10 pages, 8 figures, to be published to J. Phys. Soc. Jpn Vol.72 No.1
(accepted
A two dimensional model for ferromagnetic martensites
We consider a recently introduced 2-D square-to-rectangle martensite model
that explains several unusual features of martensites to study ferromagnetic
martensites. The strain order parameter is coupled to the magnetic order
parameter through a 4-state clock model. Studies are carried out for several
combinations of the ordering of the Curie temperatures of the austenite and
martensite phases and, the martensite transformation temperature. We find that
the orientation of the magnetic order which generally points along the short
axis of the rectangular variant, changes as one crosses the twin or the
martensite-austenite interface. The model shows the possibility of a subtle
interplay between the growth of strain and magnetic order parameters as the
temperature is decreased. In some cases, this leads to qualitatively different
magnetization curves from those predicted by earlier mean field models.
Further, we find that strain morphology can be substantially altered by the
magnetic order. We have also studied the dynamic hysteresis behavior.
The corresponding dissipation during the forward and reverse cycles has
features similar to the Barkhausen's noise.Comment: 9 pages, 11 figure
Periodically modulated geometric and electronic structure of graphene on Ru(0001)
We report here on a method to fabricate and characterize highly perfect,
periodically rippled graphene monolayers and islands, epitaxially grown on
single crystal metallic substrates under controlled UHV conditions. The
periodicity of the ripples is dictated by the difference in lattice parameters
of graphene and substrate, and, thus, it is adjustable. We characterize its
perfection at the atomic scale by means of STM and determine its electronic
structure in the real space by local tunnelling spectroscopy. There are
periodic variations in the geometric and electronic structure of the graphene
monolayer. We observe inhomogeneities in the charge distribution, i.e a larger
occupied Density Of States at the higher parts of the ripples. Periodically
rippled graphene might represent the physical realization of an ordered array
of coupled graphene quantum dots. The data show, however, that for rippled
graphene on Ru(0001) both the low and the high parts of the ripples are
metallic. The fabrication of periodically rippled graphene layers with
controllable characteristic length and different bonding interactions with the
substrate will allow a systematic experimental test of this fundamental
problem.Comment: 12 pages. Contribution to the topical issue on graphene of
Semiconductor Science and Technolog
Computation of Green's function by local variational quantum compilation
Computation of the Green's function is crucial to study the properties of
quantum many-body systems such as strongly correlated systems. Although the
high-precision calculation of the Green's function is a notoriously challenging
task on classical computers, the development of quantum computers may enable us
to compute the Green's function with high accuracy even for
classically-intractable large-scale systems. Here, we propose an efficient
method to compute the real-time Green's function based on the local variational
quantum compilation (LVQC) algorithm, which simulates the time evolution of a
large-scale quantum system using a low-depth quantum circuit constructed
through optimization on a smaller-size subsystem. Our method requires shallow
quantum circuits to calculate the Green's function and can be utilized on both
near-term noisy intermediate-scale and long-term fault-tolerant quantum
computers depending on the computational resources we have. We perform a
numerical simulation of the Green's function for the one- and two-dimensional
Fermi-Hubbard model up to sites lattice (32 qubits) and demonstrate
the validity of our protocol compared to a standard method based on the Trotter
decomposition. We finally present a detailed estimation of the gate count for
the large-scale Fermi-Hubbard model, which also illustrates the advantage of
our method over the Trotter decomposition.Comment: 22 pages, 13 figure
Thermodynamic Geometry of black hole in the deformed Horava-Lifshitz gravity
We investigate the thermodynamic geometry and phase transition of
Kehagias-Sfetsos black hole in the deformed Horava-Lifshitz gravity with
coupling constant . The phase transition in black hole
thermodynamics is thought to be associated with the divergence of the
capacities. And the structures of these divergent points are studied. We also
find that the thermodynamic curvature produced by the Ruppeiner metric is
positive definite for all and is divergence at
corresponded to the divergent points of and . These results
suggest that the microstructure of the black hole has an effective repulsive
interaction, which is very similar to the ideal gas of fermions. These may
shine some light on the microstructure of the black hole.Comment: 5 pages, 3 figure
Valence changes associated with the metal-insulator transition in BiLaNiO
Perovskite-type BiNiO is an insulating antiferromagnet in which a charge
disproportionation occurs at the Bi site. La substitution for Bi suppresses the
charge disproportionation and makes the system metallic. We have measured the
photoemission and x-ray absorption (XAS) spectra of BiLaNiO
to investigate how the electronic structure changes with La doping. From Ni
XAS, we observed an increase of the valence of Ni from 2+ toward 3+.
Combined with the core-level photoemission study, it was found that the average
valence of Bi remains and that the Ni valence behaves as , that is, La substitution results in hole doping at the Ni sites. In
the valence-band photoemission spectra, we observed a Fermi cutoff for ,
consistent with the metallic behavior of the La-doped compounds. The Ni
XAS, Ni core-level photoemission, and valence-band photoemission spectra
were analyzed by configuration-interaction cluster-model calculation, and the
spectral line shapes were found to be consistent with the gradual Ni
Ni valence change.Comment: 6 pages, 7 figure
- …