317 research outputs found
Magnetic ordering in Co2+-containing layered double hydroxides via the low-temperature heat capacity and magnetisation study
The low-temperature heat capacity and the magnetisation of Co2+
n Al3+ layered double hydroxides (LDH) with the
cobalt-to-aluminium ratio n = 2 and 3 and intercalated with different anions have been studied in a wide range of
magnetic fields up to 50 kOe. The heat capacity, C(T), was found to demonstrate a Schottky-like anomaly
observed as a broad local maximum in the temperature dependence below 10 K. The effect is caused by a
splitting of the ground-state Kramers doublet of Co2+ in the internal exchange field and correlates with magnetic
ordering in these LDH. In low applied fields, the temperature-dependent dc magnetic susceptibility demonstrates
a pronounced rise, which is associated with an onset of magnetic ordering. Both the heat capacity anomaly and
the magnetic susceptibility peak are more pronounced for the LDH with n = 2 than for those with n = 3. This
feature is associated with an excess of the honeycomb-like Co–Al coordination (which corresponds to a 2:1
Co–Al ordering) over the statistical cation distribution in Co2Al LDH, while a rather random cobalt-aluminium
distribution is typical for Co3Al LDH. The temperature of the Schottky-like anomaly measured in a zero field is
independent of the interlayer distance. Application of the magnetic field results in a widening of the anomaly
range and a shift to higher temperatures. The observed experimental data are typical for a cluster spin glass
ground state.publishe
Tunneling spectroscopy in the magnetic superconductor TmNi2B2C
We present new measurements about the tunneling conductance in the
borocarbide superconductor TmNiBC. The results show a very good
agreement with weak coupling BCS theory, without any lifetime broadening
parameter, over the whole sample surface. We detect no particular change of the
tunneling spectroscopy below 1.5K, when both the antiferromagnetic (AF) phase
and the superconducting order coexist.Comment: Submitted to Phys. Rev. B, Rapid Communication
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