Topic
Mott transition
About: Mott transition is a research topic. Over the lifetime, 2444 publications have been published within this topic receiving 78401 citations.
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TL;DR: In this paper, the effect of impurity pinning on a one-dimensional half-filled electron system, expressed in terms of a phase Hamiltonian with the charge degree of freedom, was studied.
Abstract: We study the effect of impurity pinning on a one-dimensional half-filled electron system, which is expressed in terms of a phase Hamiltonian with the charge degree of freedom. Within the classical treatment, the pinned state is examined numerically. The Mott glass, which has been pointed out by Orignac et al. [Phys. Rev. Lett. 83 (1999) 2378], appears in the intermediate region where the impurity potential competes with the commensurate potential. Such a state is verified by calculating the soliton formation energy, the local restoring force around the pinned state and the optical conductivity.
1 citations
01 Jan 2010
TL;DR: In this article, the authors performed a systematic photoemission study of the chemical potential shift as a function of doping in a pnictide system based on BaFe2As2.
Abstract: Angle-resloved photoemission spectroscopy (ARPES) is a
powerful technique to study the electronic structure in solids. Its
unique ability of resolving the energy and momentum information of
electrons inside a solid provides an essential tool in measuring
the electronic structure of solids. ARPES has made great
contributions in the understanding of correlated system such as
high-Tc superconductors and ruthenates. The
Metal-insulator transition is a fundamental problem in condensed
matter physics. The calcium substituted strontium ruthenate,
Ca2-xSrxRuO4,
provides a good platform to study the metal-insulator transition in
multi-orbital systems. This system has a complex phase diagram that
evolves from a p -wave superconductor
to a Mott insulator. One of important projects of this thesis
focuses on
Ca2-xSrxRuO4
The growing evidence for coexistence of itinerant electrons and
local moments in transition metals with nearly degenerate d
orbitals suggests that one or more electron orbitals undergo a Mott
transition while the others remain itinerant. We have observed a
novel orbital selective Mott transition (OSMT) in
Ca1.8Sr0.2RuO4
by ARPES. While we observed two sets of dispersing bands and Fermi
surfaces (FSs) associated with the doubly-degenerate
dyz and dzx orbitals,
the Fermi surface associated with the dxy
orbital which has a wider bandwidth is missing as a consequence of
selective Mott localization. Our theoretical calculations have
demonstrated that this unusual OSMT is mainly driven by the
combined effects of inter-orbital carrier transfer, superlattice
potentials and orbital degeneracy, whereas the bandwidth difference
plays a less important role. Another important project of this
thesis focuses on the recently discovered iron-pnictides
superconductors. The idea of inter-FS scattering associated with
the near-nesting condition has been proposed to explain the
superconductivity in the pnictides. The near-nesting condition
varies upon the carrier doping which shifts the chemical potential.
We have performed a systematic photoemission study of the chemical
potential shift as a function of doping in a pnictide system based
on BaFe2As2. The
experimentally determined chemical potential shift is consistent
with the prediction of a rigid band shift picture by the
renormalized first-principle band calculations. This leads to an
electron-hole asymmetry (EHA) due to different Fermi velocities for
different FS sheets, which can be calculated from the Lindhard
function of susceptibility. This built-in EHA from the band
structure, which is fully consistent with the experimental phase
diagram, strongly supports that inter-FS scattering over the
near-nesting Fermi surfaces plays a vital role in the
superconductivity of the iron pnictides.
1 citations
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TL;DR: In this paper, the role of generic scale invariance in a Mott transition from a U(1) spin-liquid insulator to a Landau Fermi-liquid metal was investigated.
Abstract: We investigate the role of generic scale invariance in a Mott transition from a U(1) spin-liquid insulator to a Landau Fermi-liquid metal, where there exist massless degrees of freedom in addition to quantum critical fluctuations. Here, the Mott quantum criticality is described by critical charge fluctuations, and additional gapless excitations are U(1) gauge-field fluctuations coupled to a spinon Fermi surface in the spin-liquid state, which turn out to play a central role in the Mott transition. An interesting feature of this problem is that the scaling dimension of effective leading local interactions between critical charge fluctuations differs from that of the coupling constant between U(1) gauge fields and matter-field fluctuations in the presence of a Fermi surface. As a result, there appear dangerously irrelevant operators, which can cause conceptual difficulty in the implementation of renormalization group (RG) transformations. Indeed, we find that the curvature term along the angular direction of the spinon Fermi surface is dangerously irrelevant at this spin-liquid Mott quantum criticality, responsible for divergence of the self-energy correction term in U(1) gauge-field fluctuations. Performing the RG analysis in the one-loop level based on the dimensional regularization method, we reveal that such extremely overdamped dynamics of U(1) gauge-field fluctuations, which originates from the emergent one-dimensional dynamics of spinons, does not cause any renormalization effects to the effective dynamics of both critical charge fluctuations and spinon excitations. However, it turns out that the coupling between U(1) gauge-field fluctuations and both matter-field excitations still persists at this Mott transition, which results in novel mean-field dynamics to explain the nature of the spin-liquid Mott quantum criticality.
1 citations
25 Aug 2004
TL;DR: In this article, single-particle excitations in the Mott insulator phase of a Bose gas in an optical lattice were studied and the existence of an energy gap between the particle and hole excitations was directly probed by an output coupling experiment.
Abstract: We study single-particle excitations in the Mott insulator phase of a Bose gas in an optical lattice. The characteristic feature of the single-particle spectrum in the Mott insulator phase is the existence of an energy gap between the particle and hole excitations. We show that this energy gap can be directly probed by an output coupling experiment. We apply the general expression for the output current derived by Luxat and Griffin, which is given in terms ofthe single-particle Green’s functions of a trapped Bose gas, to the Mott insulator phase using the Bose-Hubbard model. We find that the energy spectrum of the momentum-resolved output current exhibits two characteristic peaks corresponding to the particle and hole excitations, and thus it can be used to detect the transition point from the Mott insulator to superfluid phase where the energy gap disappears.
1 citations
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1 citations