480 research outputs found
Angle-resolved photoemission spectroscopy of perovskite-type transition-metal oxides and their analyses using tight-binding band structure
Nowadays it has become feasible to perform angle-resolved photoemission
spectroscopy (ARPES) measurements of transition-metal oxides with
three-dimensional perovskite structures owing to the availability of
high-quality single crystals of bulk and epitaxial thin films. In this article,
we review recent experimental results and interpretation of ARPES data using
empirical tight-binding band-structure calculations. Results are presented for
SrVO (SVO) bulk single crystals, and LaSrFeO (LSFO) and
LaSrMnO (LSMO) thin films. In the case of SVO, from comparison
of the experimental results with calculated surface electronic structure, we
concluded that the obtained band dispersions reflect the bulk electronic
structure. The experimental band structures of LSFO and LSMO were analyzed
assuming the G-type antiferromagnetic state and the ferromagnetic state,
respectively. We also demonstrated that the intrinsic uncertainty of the
electron momentum perpendicular to the crystal surface is important for the
interpretation of the ARPES results of three-dimensional materials.Comment: 25 pages, 12 figure
Graphical representation of the partition function for a 1-D delta-function Bose gas
One-dimensional repulsive delta-function bose system is studied. By only
using the Bethe ansatz equation, n-particle partition functions are exactly
calculated. From this expression for the n-particle partition function, the
n-particle cluster integral is derived. The results completely agree with those
of the thermal Bethe ansatz (TBA). This directly proves the validity of the
TBA. The theory of partitions and graphs is used to simplify the discussion.Comment: 15 page
The Coupled Modified Korteweg-de Vries Equations
Generalization of the modified KdV equation to a multi-component system, that
is expressed by , is studied. We apply a new extended version of the inverse
scattering method to this system. It is shown that this system has an infinite
number of conservation laws and multi-soliton solutions. Further, the initial
value problem of the model is solved.Comment: 26 pages, LaTex209 file, uses jpsj.st
Partition Function for a 1-D delta-function Bose Gas
The N-particle partition function of a one-dimensional -function bose
gas is calculated explicitly using only the periodic boundary condition (the
Bethe ansatz equation). The N-particles cluster integrals are shown to be the
same as those by the thermal Bethe ansatz method.Comment: 30 page
Exactly solvable Wadati potentials in the PT-symmetric Gross-Pitaevskii equation
This note examines Gross-Pitaevskii equations with PT-symmetric potentials of
the Wadati type: . We formulate a recipe for the construction of
Wadati potentials supporting exact localised solutions. The general procedure
is exemplified by equations with attractive and repulsive cubic nonlinearity
bearing a variety of bright and dark solitons.Comment: To appear in Proceedings of the 15 Conference on Pseudo-Hermitian
Hamiltonians in Quantum Physics, May 18-23 2015, Palermo, Italy (Springer
Proceedings in Physics, 2016
Gradual Disappearance of the Fermi Surface near the Metal-Insulator Transition in LaSrMnO
We report the first observation of changes in the electronic structure of
LaSrMnO (LSMO) across the filling-control metal-insulator
(MI) transition by means of in situ angle-resolved photoemission spectroscopy
(ARPES) of epitaxial thin films. The Fermi surface gradually disappears near
the MI transition by transferring the spectral weight from the coherent band
near the Fermi level () to the lower Hubbard band, whereas a pseudogap
behavior also exists in the ARPES spectra in the close vicinity of for
the metallic LSMO. These results indicate that the spectral weight transfer
derived from strong electron-electron interaction dominates the gap formation
in LSMO associated with the filling-control MI transition.Comment: 11 pages, 4 figure
In-situ photoemission study of Pr_{1-x}Ca_xMnO_3 epitaxial thin films with suppressed charge fluctuations
We have performed an {\it in-situ} photoemission study of Pr_{1-x}Ca_xMnO_3
(PCMO) thin films grown on LaAlO_3 (001) substrates and observed the effect of
epitaxial strain on the electronic structure. We found that the chemical
potential shifted monotonically with doping, unlike bulk PCMO, implying the
disappearance of incommensurate charge fluctuations of bulk PCMO. In the
valence-band spectra, we found a doping-induced energy shift toward the Fermi
level (E_F) but there was no spectral weight transfer, which was observed in
bulk PCMO. The gap at E_F was clearly seen in the experimental band dispersions
determined by angle-resolved photoemission spectroscopy and could not be
explained by the metallic band structure of the C-type antiferromagnetic state,
probably due to localization of electrons along the ferromagnetic chain
direction or due to another type of spin-orbital ordering.Comment: 5 pages, 4 figure
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