855 research outputs found
Recommended from our members
Use of focus groups to explore service users’experiences and inform future service development needs in an outpatient service
Quantum Spin Ice Response to a Magnetic Field in the Dipole-Octupole Pyrochlore CeZrO
We report new heat capacity measurements on single crystal CeZrO
down to 0.1 K in a magnetic field along the direction.
These new measurements show that the broad hump in the zero-field heat capacity
moves higher in temperature with increasing field strength and is split into
two humps by the field at 2 T. These separate features
are due to the decomposition of the pyrochlore lattice into effectively
decoupled chains for fields in this direction: one set of chains
(-chains) is polarized by the field while the other (-chains)
remains free. Our theoretical modelling suggests that the -chains are
close to a critical state, with nearly-gapless excitations. We also report new
elastic and inelastic neutron scattering measurements on single crystal
CeZrO in and magnetic fields at
temperatures down to 0.03 K. The elastic scattering behaves consistently with
the formation of independent chains for a field, while the
field produces a single field-induced magnetic Bragg peak at and equivalent wavevectors, indicating a polarized spin ice for fields
above 3 T. For both and fields, our
inelastic neutron scattering results show an approximately-dispersionless
continuum of scattering that increases in both energy and intensity with
increasing field strength. By modelling the complete set of experimental data
using numerical linked cluster and semiclassical molecular dynamics
calculations, we demonstrate the dominantly multipolar nature of the exchange
interactions in CeZrO and the smallness of the parameter
which controls the mixing between dipolar and octupolar degrees of freedom.
These results support previous estimates of the microscopic exchange
parameters.Comment: 20 pages, 10 figure
Reply to "Comment on: 'Case for a U(1) Quantum Spin Liquid Ground State in the Dipole-Octupole Pyrochlore ' "
In his comment [arXiv:2209.03235], S. W. Lovesey argues that our analysis of
neutron scattering experiments performed on CeZrO is invalid.
Lovesey argues that we have not properly accounted for the higher-order
multipolar contributions to the magnetic scattering and that our use of
pseudospin- operators to describe the scattering is inappropriate. In this
reply, we show that the multipolar corrections discussed by Lovesey only become
significant at scattering wavevectors exceeding those accessed in our
experiments. This in no way contradicts or undermines our work, which never
claimed a direct observation of scattering from higher-order multipoles. We
further show that Lovesey's objections to our use of pseudospins are unfounded,
and that the pseudospin operators are able to describe all magnetic scattering
processes at the energy scale of our experiments, far below the crystal field
gap. Finally, we comment on certain assumptions in Lovesey's calculations of
the scattering amplitude which are inconsistent with experiment.Comment: 6 pages, 1 figur
Revisiting the Local Scaling Hypothesis in Stably Stratified Atmospheric Boundary Layer Turbulence: an Integration of Field and Laboratory Measurements with Large-eddy Simulations
The `local scaling' hypothesis, first introduced by Nieuwstadt two decades
ago, describes the turbulence structure of stable boundary layers in a very
succinct way and is an integral part of numerous local closure-based numerical
weather prediction models. However, the validity of this hypothesis under very
stable conditions is a subject of on-going debate. In this work, we attempt to
address this controversial issue by performing extensive analyses of turbulence
data from several field campaigns, wind-tunnel experiments and large-eddy
simulations. Wide range of stabilities, diverse field conditions and a
comprehensive set of turbulence statistics make this study distinct
Genomotyping of Coxiella burnetii Using Microarrays Reveals a Conserved Genomotype for Hard Tick Isolates
C. burnetii is a Gram-negative intracellular Y-proteobacteria that causes the zoonotic disease Q fever. Q fever can manifest as an acute or chronic illness. Different typing methods have been previously developed to classify C. burnetii isolates to explore its pathogenicity. Here, we report a comprehensive genomotyping method based on the presence or absence of genes using microarrays. The genomotyping method was then tested in 52 isolates obtained from different geographic areas, different hosts and patients with different clinical manifestations. The analysis revealed the presence of 10 genomotypes organized into 3 groups, with a topology congruent with that obtained through multi-spacer typing. We also found that only 4 genomotypes were specifically associated with acute Q fever, whereas all of the genomotypes could be associated to chronic human infection. Serendipitously, the genomotyping results revealed that all hard tick isolates, including the Nine Mile strain, belong to the same genomotype
- …