2,989 research outputs found
Time-Reversal Symmetry-Breaking Superconductivity in Heavy Fermion PrOs4Sb12 detected by Muon Spin Relaxation
We report on muon spin relaxation measurements of the 4f^2-based
heavy-fermion superconductor filled-skutterudite PrOs4Sb12. The results reveal
the spontaneous appearance of static internal magnetic fields below the
superconducting transition temperature, providing unambiguous evidence for the
breaking of time-reversal symmetry in the superconducting state. A discussion
is made on which of the spin or orbital component of Cooper pairs carries a
nonzero momentum.Comment: 5 pages with 3 figure
Magnetic Phase Diagram of the Hole-doped CaNaCuOCl Cuprate Superconductor
We report on the magnetic phase diagram of a hole-doped cuprate
CaNaCuOCl, which is free from buckling of CuO
planes, determined by muon spin rotation and relaxation. It is characterized by
a quasi-static spin glass-like phase over a range of sodium concentration
(), which is held between long range antiferromagnetic
(AF) phase () and superconducting phase where the system is
non-magnetic for . The obtained phase diagram qualitatively agrees
well with that commonly found for hole-doped high-\tc cuprates, strongly
suggesting that the incomplete suppression of the AF order for is an
essential feature of the hole-doped cuprates.Comment: 5 pages, submitted to Phys. Rev. Let
Spin dynamics and spin freezing in the triangular lattice antiferromagnets FeGa2S4 and NiGa2S4
Magnetic susceptibility and muon spin relaxation (muSR) experiments have been
carried out on the quasi-2D triangular-lattice spin S = 2 antiferromagnet
FeGa2S4. The muSR data indicate a sharp onset of a frozen or nearly-frozen spin
state at T* = 31(2) K, twice the spin-glass-like freezing temperature T_f =
16(1) K. The susceptibility becomes field dependent below T*, but no sharp
anomaly is observed in any bulk property. A similar transition is observed in
muSR data from the spin-1 isomorph NiGa2S4. In both compounds the dynamic muon
spin relaxation rate lambda_d(T) above T* agrees well with a calculation of
spin-lattice relaxation by Chubukov, Sachdev, and Senthil in the renormalized
classical regime of a 2D frustrated quantum antiferromagnet. There is no firm
evidence for other mechanisms. At low temperatures lambda_d(T) becomes
temperature independent in both compounds, indicating persistence of spin
dynamics. Scaling of lambda_d(T) between the two compounds is observed from
~T_f to ~1.5T*. Although the muSR data by themselves cannot exclude a truly
static spin component below T*, together with the susceptibility data they are
consistent with a slowly-fluctuating "spin gel" regime between T_f and T*. Such
a regime and the absence of a divergence in lambda_d(T) at T* are features of
two unconventional mechanisms: (1) binding/unbinding of Z_2 vortex excitations,
and (2) impurity spins in a nonmagnetic spin-nematic ground state. The absence
of a sharp anomaly or history dependence at T* in the susceptibility of
FeGa2S4, and the weakness of such phenomena in NiGa2S4, strongly suggest
transitions to low-temperature phases with unconventional dynamics.Comment: 13 pages, 6 figures, accepted for publication in Physical Review
Detection of Neutron Scattering from Phase IV of Ce0.7La0.3B6: A Confirmation of the Octupole Order
We have performed a single crystal neutron scattering experiment on
Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically.
Below the phase transition temperature 1.5 K of phase IV, weak but distinct
superlattice reflections at the scattering vector (h/2,h/2,l/2) (h, l = odd
number) have been observed by neutron scattering for the first time. The
intensity of the superlattice reflections is stronger for high scattering
vectors, which is quite different from the usual magnetic form factor of
magnetic dipoles. This result directly evidences that the order parameter of
phase IV has a complex magnetization density, consistent with the recent
experimental and theoretical prediction in which the order parameter is the
magnetic octupoles Tbeta with Gamma5 symmetry of point group Oh. Neutron
scattering experiments using short wavelength neutrons, as done in this study,
could become a general method to study the high-rank multipoles in f electron
systems.Comment: 4 pages, 4 figure
Building Capacity for Public Health 3.0: Introducing implementation science into an MPH curriculum
Background
Many public health programs fail because of an inability to implement tested interventions in diverse, complex settings. The field of implementation science is engaged in developing strategies for successful implementation, but current training is primarily researcher-focused. To tackle the challenges of the twenty-first century, public health leaders are promoting a new model titled Public Health 3.0 where public health practitioners become “chief health strategists” and develop interdisciplinary skills for multisector engagement to achieve impact. This requires broad training for public health practitioners in implementation science that includes the allied fields of systems and design thinking, quality improvement, and innovative evaluation methods. At UNC Chapel Hill’s Gillings School of Global Public Health, we created an interdisciplinary set of courses in applied implementation science for Master of Public Health (MPH) students and public health practitioners. We describe our rationale, conceptual approach, pedagogy, courses, and initial results to assist other schools contemplating similar programs.
Methods
Our conceptual approach recognized the vital relationship between implementation research and practice. We conducted a literature review of thought leaders in public health to identify skill areas related to implementation science that are priorities for the future workforce. We also reviewed currently available training programs in implementation science to understand their scope and objectives and to assess whether any of these would be a fit for these priorities. We used a design focused implementation framework to create four linked courses drawing from multiple fields such as engineering, management, and the social sciences and emphasizing application through case studies. We validated the course content by mapping them to implementation science competencies in the literature.
Results
To date, there is no other program that provides comprehensive interdisciplinary skills in applied implementation science for MPH students. As of April 2018, we have offered a total of eleven sections of the four courses, with a total enrollment of 142, of whom 127 have been master’s-level students in the school of public health. Using Kirkpatrick’s Model, we found positive student reaction, learning, and behavior. Many students have completed applied implementation science focused practicums, master’s papers, and special studies.
Conclusions
A systematically designed interdisciplinary curriculum in applied implementation science for MPH students has been found by students to be a useful set of skills. Students have demonstrated the capability to master this material and incorporate it into their practicums and master’s papers
The new high field photoexcitation muon spectrometer at the ISIS pulsed neutron and muon source
A high power pulsed laser system has been installed on the high magnetic
field muon spectrometer (HiFi) at the ISIS pulsed neutron and muon source,
situated at the STFC Rutherford Appleton Laboratory in the UK. The upgrade
enables one to perform light-pump muon-probe experiments under a high magnetic
field, which opens new applications of muon spin spectroscopy. In this report
we give an overview of the principle of the HiFi Laser system, and describe the
newly developed techniques and devices that enable precisely controlled
photoexcitation of samples in the muon instrument. A demonstration experiment
illustrates the potential of this unique combination of the photoexcited system
and avoided level crossing technique.Comment: 12 pages, 7 figures, and 2 table
Muon spin rotation and relaxation in magnetic materials
A review of the muon spin rotation and relaxation (SR) studies on
magnetic materials published from July 1993 is presented. It covers the
investigation of magnetic phase diagrams, of spin dynamics and the analysis of
the magnetic properties of superconductors. We have chosen to focus on selected
experimental works in these different topics. In addition, a list of published
works is provided.Comment: Review article, 59 pages, LaTeX with IoP macro
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