1,568 research outputs found
Atmospheric frontal zone studies
The research supported by this contract and directed Activities in the inversion and interpretation of data produced by the Nimbus-7 scanning multichannel microwave radiometer (SMMR) are reported. There were five principal subjects: (1) modeling of the emissivity of foam patches on the ocean surface; (2) inversion of radiometric data by a multidimensional algorithm; (3) an operational water vapor retrieval algorithm; (4) inference of Antarctic firm accumulation rates; and (5) inference of water vapor over the Arctic sea ice
Destroying coherence in high temperature superconductors with current flow
The loss of single-particle coherence going from the superconducting state to
the normal state in underdoped cuprates is a dramatic effect that has yet to be
understood. Here, we address this issue by performing angle resolved
photoemission spectroscopy (ARPES) measurements in the presence of a transport
current. We find that the loss of coherence is associated with the development
of an onset in the resistance, in that well before the midpoint of the
transition is reached, the sharp peaks in the ARPES spectra are completely
suppressed. Since the resistance onset is a signature of phase fluctuations,
this implies that the loss of single-particle coherence is connected with the
loss of long-range phase coherence.Comment: 7 pages, 7 figure
Orbital and spin chains in ZnV2O4
Our powder inelastic neutron scattering data indicate that \zvo is a system
of spin chains that are three dimensionally tangled in the cubic phase above 50
K due to randomly occupied orbitals of V () ions. Below
50 K in the tetragonal phase, the chains become straight due to
antiferro-orbital ordering. This is evidenced by the characteristic wave vector
dependence of the magnetic structure factor that changes from symmetric to
asymmetric at the cubic-to-tetragonal transition
Nano-magnetic droplets and implications to orbital ordering in La1-xSrxCoO3
Inelastic cold neutron scattering on LaCoO3 provided evidence for a distinct
low energy excitation at 0.6 meV coincident with the thermally induced magnetic
transition. Coexisting strong ferromagnetic (FM) and weaker antiferromagnetic
(AFM) correlations that are dynamic follow the activation to the excited state,
identified as the intermediate S=1 spin triplet. This is indicative of
dynamical orbital ordering favoring the observed magnetic interactions. With
hole doping as in La1-xSrxCoO3, the FM correlations between Co spins become
static and isotropically distributed due to the formation of FM droplets. The
correlation length and condensation temperature of these droplets increase
rapidly with metallicity due to the double exchange mechanism.Comment: To appear in Phys. Rev. Let
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