1,712 research outputs found
A parity-breaking electronic nematic phase transition in the spin-orbit coupled metal CdReO
Strong electron interactions can drive metallic systems toward a variety of
well-known symmetry-broken phases, but the instabilities of correlated metals
with strong spin-orbit coupling have only recently begun to be explored. We
uncovered a multipolar nematic phase of matter in the metallic pyrochlore
CdReO using spatially resolved second-harmonic optical anisotropy
measurements. Like previously discovered electronic nematic phases, this
multipolar phase spontaneously breaks rotational symmetry while preserving
translational invariance. However, it has the distinguishing property of being
odd under spatial inversion, which is allowed only in the presence of
spin-orbit coupling. By examining the critical behavior of the multipolar
nematic order parameter, we show that it drives the thermal phase transition
near 200 kelvin in CdReO and induces a parity-breaking lattice
distortion as a secondary order.Comment: 9 pages main text, 4 figures, 10 pages supplementary informatio
Doping evolution and polar surface reconstruction of the infinite-layer cuprate SrLaCuO
We use angle-resolved photoemission spectroscopy to study the doping
evolution of infinite-layer SrLaCuO thin films grown by
molecular-beam epitaxy. At low doping, the material exhibits a dispersive lower
Hubbard band typical of the superconducting cuprate parent compounds. As
carriers are added to the system, a continuous evolution from charge-transfer
insulator to superconductor is observed, with the initial lower Hubbard band
pinned well below the Fermi level and the development of a coherent low-energy
band with electron doping. This two-component spectral function emphasizes the
important role that strong local correlations play even at relatively high
doping levels. Electron diffraction probes reveal a surface
reconstruction of the material at low doping levels. Using a number of simple
assumptions, we develop a model of this reconstruction based on the polar
nature of the infinite-layer structure. Finally, we provide evidence for a
thickness-controlled transition in ultrathin films of SrCuO grown on
nonpolar SrTiO, highlighting the diverse structural changes that can occur
in polar complex oxide thin films
Nodeless superconductivity arising from strong (pi,pi) antiferromagnetism in the infinite-layer electron-doped cuprate Sr1-xLaxCuO2
The asymmetry between electron and hole doping remains one of the central
issues in high-temperature cuprate superconductivity, but our understanding of
the electron-doped cuprates has been hampered by apparent discrepancies between
the only two known families: Re2-xCexCuO4 and A1-xLaxCuO2. Here we report in
situ angle-resolved photoemission spectroscopy measurements of
epitaxially-stabilized films of Sr1-xLaxCuO2 synthesized by oxide
molecular-beam epitaxy. Our results reveal a strong coupling between electrons
and (pi,pi) antiferromagnetism that induces a Fermi surface reconstruction
which pushes the nodal states below the Fermi level. This removes the hole
pocket near (pi/2,pi/2), realizing nodeless superconductivity without requiring
a change in the symmetry of the order parameter and providing a universal
understanding of all electron-doped cuprates
Tetrahedral Symmetry in Ground- and Low-Lying States of Exotic A ~ 110 Nuclei
Recent theoretical calculations predict a possible existence of nuclei with
tetrahedral symmetry: more precisely, the mean-field hamiltonians of such
nuclei are symmetric with respect to double point-group Td. In this paper, we
focus on the neutron-rich Zirconium isotopes as an example and present
realistic mean-field calculations which predict tetrahedral ground-state
configurations in 108,110Zr and low-lying excited states of tetrahedral
symmetry in a number of N > 66 isotopes. The motivations for focusing on these
nuclei, as well as a discussion of the possible experimental signatures of
tetrahedral symmetry are also presented.Comment: Accepted in Phys. Rev. C - Rapid Communication
Nuclear Tetrahedral Symmetry: Possibly Present Throughout the Periodic Table
More than half a century after the fundamental, spherical shell structure in
nuclei has been established, theoretical predictions indicate that the
shell-gaps comparable or even stronger than those at spherical shapes may
exist. Group-theoretical analysis supported by realistic mean-field
calculations indicate that the corresponding nuclei are characterized by the
('double-tetrahedral') group of symmetry, exact or approximate. The
corresponding strong shell-gap structure is markedly enhanced by the existence
of the 4-dimensional irreducible representations of the group in question and
consequently it can be seen as a geometrical effect that does not depend on a
particular realization of the mean-field. Possibilities of discovering the
corresponding symmetry in experiment are discussed.Comment: 4 pages in LaTeX and 4 figures in eps forma
Impact of aerobic and resistance exercise combination on physical self-perceptions and self-esteem in women with obesity with one-year follow-up
The effectiveness of an exercise intervention including both aerobics and resistance training components in improving physical self-perceptions and global self-esteem (GSE) in women with obesity was examined. An experimental design with a one-year follow-up was used. Women with obesity (n = 72) participated in a structured exercise programme for 12 weeks after being randomised into a control and an exercise group. Exercise self-efficacy, body attractiveness, physical strength, sport competence, physical condition, physical self-worth, and GSE were measured at pre-intervention, early intervention, mid-intervention, immediately after the intervention, and five times following programme termination at 1, 3, 6, 9, and 12 months, respectively. Analyses of covariance revealed exercise effects for all of the dependent variables except for body attractiveness. Generally, exercise effects lasted between 6 and 12 months. A 12-week physical exercise programme including aerobic and resistance training components has the potential to improve physical self-perceptions and self-esteem in women with obesity
Electronic nematic order in the normal state of strontium ruthenate
Despite significant achievements in characterizing the properties of
SrRuO over the last three decades, the precise nature of its electronic
ground state is still unresolved. In this work, we provide a missing piece of
the puzzle by uncovering evidence of electronic nematic order in the normal
state of SrRuO, revealed by ultrafast time-resolved optical dichroism
measurements of uniaxially strained thin films. This nematic order, whose
domains are aligned by the strain, spontaneously breaks the four-fold
rotational symmetry of the crystal. The temperature dependence of the dichroism
resembles an Ising-like order parameter, and optical pumping induces a coherent
oscillation of its amplitude mode. A microscopic model of intra-unit-cell
nematic order is presented, highlighting the importance of Coulomb repulsion
between neighboring oxygen -orbitals. The existence of electronic nematic
order in the normal state of SrRuO may have consequences for the form
and mechanism of superconductivity in this material
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