12,466 research outputs found
Magnetic properties of geometrically frustrated SrGd2O4
A study of the magnetic properties of the frustrated rare earth oxide SrGd2O4
has been completed using bulk property measurements of magnetization,
susceptibility and specific heat on single crystal samples. Two zero-field
phase transitions have been identified at 2.73 and 0.48 K. For the field, H,
applied along the a and b axes, a single boundary is identified that delineates
the transition from a low field, low temperature magnetically ordered regime to
a high field, high temperature paramagnetic phase. Several field-induced
transitions, however, have been observed with H || c. The measurements have
been used to map out the magnetic phase diagram of SrGd2O4, suggesting that it
is a complex system with several competing magnetic interactions. The
low-temperature magnetic behavior of SrGd2O4 is very different compared to the
other SrLn2O4 (Ln = Lanthanide) compounds, even though all of the SrLn2O4
compounds are isostructural, with the magnetic ions forming a low-dimensional
lattice of zigzag chains that run along the c axis. The differences are likely
to be due to the fact that in the ground state Gd3+ has zero orbital angular
momentum and therefore the spin-orbit interactions, which are crucial for other
SrLn2O4 compounds, can largely be neglected. Instead, given the relatively
short Gd3+-Gd3+ distances in SrGd2O4, dipolar interactions must be taken into
account for this antiferromagnet alongside the Heisenberg exchange terms.Comment: 10 pages, 9 figure
Promoting cultural competence in health care through a research based intervention in the UK.
There is an urgent need to develop cultural competence among nurses and other care workers if they are to meet the needs of the diverse populations they serve, yet there is limited clarity about what this means, or how it can be measured. To date few attempts have been made to measure the effectiveness of education and training programmes which are designed to promote cultural competence. A research project commissioned by mental health service providers was undertaken to deal with the increasing need for cultural competence in a number of mental health care settings. It involved the delivery of a training intervention with an assessment of cultural competence before and after the intervention. The training intervention was negotiated with the participating teams and was based on the Papadopoulos, Tilki & Taylor model (1998). The project included the design and development of a tool for assessing cultural competence (CCATool). The paper discusses the challenges faced by the trainers during this intervention and proposes a set of principles for the development of effective cultural competence programmes
Studies of the superconducting properties of Sn1-xInxTe (x=0.38 to 0.45) using muon-spin spectroscopy
The superconducting properties of Sn1-xInxTe (x = 0.38 to 0.45) have been
studied using magnetization and muon-spin rotation or relaxation (muSR)
measurements. These measurements show that the superconducting critical
temperature Tc of Sn1-xInxTe increases with increasing x, reaching a maximum at
around 4.8 K for x = 0.45. Zero-field muSR results indicate that time-reversal
symmetry is preserved in this material. Transverse-field muon-spin rotation has
been used to study the temperature dependence of the magnetic penetration depth
lambda(T) in the mixed state. For all the compositions studied, lambda(T) can
be well described using a single-gap s-wave BCS model. The magnetic penetration
depth at zero temperature lambda(0) ranges from 500 to 580 nm. Both the
superconducting gap Delta(0) at 0 K and the gap ratio Delta(0)/kBTc indicate
that Sn1-xInxTe (x = 0.38 to 0.45) should be considered as a superconductor
with intermediate to strong coupling.Comment: 7 pages, 6 figures, 3 table
Comparative study of the centrosymmetric and non-centrosymmetric superconducting phases of Re3W using muon-spin spectroscopy and heat capacity measurements
We compare the low-temperature electronic properties of the centrosymmetric
(CS) and non-centrosymmetric (NCS) phases of Re3W using muon-spin spectroscopy
and heat capacity measurements. The zero-field muSR results indicate that
time-reversal symmetry is preserved for both structures of Re3W.
Transverse-field muon spin rotation has been used to study the temperature
dependence of the penetration depth lambda(T) in the mixed state. For both
phases of Re3W, lambda(T) can be explained using a single-gap s-wave BCS model.
The magnetic penetration depth at zero temperature, lambda(0), is 164(7) and
418(6) nm for the centrosymmetric and the non-centrosymmetric phases of Re3W
respectively. Low-temperature specific heat data also provide evidence for an
s-wave gap-symmetry for the two phases of Re3W. Both the muSR and heat capacity
data show that the CS material has a higher Tc and a larger superconducting gap
Delta(0) at 0 K than the NCS compound. The ratio Delta(0)/kBTc indicates that
both phases of Re3W should be considered as strong-coupling superconductors.Comment: 7 pages, to appear in Physical Review
Magnetic phase diagram of the antiferromagnetic pyrochlore Gd2Ti2O7
Gd2Ti2O7 is a highly frustrated antiferromagnet on a pyrochlore lattice,
where apart from the Heisenberg exchange the spins also interact via
dipole-dipole forces. We report on low-temperature specific heat measurements
performed on single crystals of Gd2Ti2O7 for three different directions of an
applied magnetic field. The measurements reveal the strongly anisotropic
behaviour of Gd2Ti2O7 in a magnetic field despite the apparent absence of a
significant single-ion anisotropy for Gd3+. The H-T phase diagrams are
constructed for H//111], H//[110] and H//[112]. The results indicate that
further theoretical work beyond a simple mean-field model is required.Comment: 4 figure
Superconducting and magnetic properties of Sr3Ir4Sn13
Magnetization and muon spin relaxation or rotation (muSR) measurements have
been performed to study the superconducting and magnetic properties of
Sr3Ir4Sn13. From magnetization measurements the lower and upper critical fields
of Sr3Ir4Sn13 are found to be 81(1) Oe and 14.4(2) kOe, respectively.
Zero-field muSR data show no sign of any magnetic ordering or weak magnetism in
Sr3Ir4Sn13. Transverse-field muSR measurements in the vortex state provided the
temperature dependence of the magnetic penetration depth. The dependence of
penetration depth with temperature is consistent with the existence of single
s-wave energy gap in the superconducting state of Sr3Ir4Sn13 with a gap value
of 0.82(2) meV at absolute zero temperature. The magnetic penetration depth at
zero temperature is 291(3) nm. The gap to Tc ratio is 2.1(1), indicates that
Sr3Ir4Sn13 should be considered as a strong-coupling superconductor.Comment: 6 pages, 5 figure
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