185 research outputs found
High-field recovery of the undistorted triangular lattice in the frustrated metamagnet CuFeO2
Pulsed field magnetization experiments extend the typical metamagnetic
staircase of CuFeO2 up to 58 T to reveal an additional first order phase
transition at high field for both the parallel and perpendicular field
configuration. Virtually complete isotropic behavior is retrieved only above
this transition, indicating the high-field recovery of the undistorted
triangular lattice. A consistent phenomenological rationalization for the field
dependence and metamagnetism crossover of the system is provided, demonstrating
the importance of both spin-phonon coupling and a small field-dependent
easy-axis anisotropy in accurately describing the magnetization process of
CuFeO2.Comment: 4 pages, 4 figure
Mapping the B,T phase diagram of frustrated metamagnet CuFeO2
The magnetic phase diagram of CuFeO2 as a function of applied magnetic field
and temperature is thoroughly explored and expanded, both for magnetic fields
applied parallel and perpendicular to the material's c-axis. Pulsed field
magnetization measurements extend the typical magnetic staircase of CuFeO2 at
various temperatures, demonstrating the persistence of the recently discovered
high field metamagnetic transition up to Tn2 ~ 11 K in both field
configurations. An extension of the previously introduced phenomenological spin
model used to describe the high field magnetization process (Phys. Rev. B, 80,
012406 (2009)) is applied to each of the consecutive low-field commensurate
spin structures, yielding a semi-quantitative simulation and intuitive
description of the entire experimental magnetization process in both relevant
field directions with a single set of parameters.Comment: 14 pages, 11 figures, submitted to Phys. Rev.
Spin susceptibility and polarization field in a dilute two-dimensional electron system in (111) silicon
We find that the polarization field, B_chi, obtained by scaling the
weak-parallel-field magnetoresistance at different electron densities in a
dilute two-dimensional electron system in (111) silicon, corresponds to the
spin susceptibility that grows strongly at low densities. The polarization
field, B_sat, determined by resistance saturation, turns out to deviate to
lower values than B_chi with increasing electron density, which can be
explained by filling of the upper electron subbands in the fully spin-polarized
regime
Temperature dependence of antiferromagnetic susceptibility in ferritin
We show that antiferromagnetic susceptibility in ferritin increases with
temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when
taken as the derivative of the magnetization at high fields (
Oe). This behavior contrasts with the decrease in temperature previously found,
where the susceptibility was determined at lower fields ( Oe). At
high fields (up to Oe) the temperature dependence of the
antiferromagnetic susceptibility in ferritin nanoparticles approaches the
normal behavior of bulk antiferromagnets and nanoparticles considering
superantiferromagnetism, this latter leading to a better agreement at high
field and low temperature. The contrast with the previous results is due to the
insufficient field range used ( Oe), not enough to saturate the
ferritin uncompensated moment.Comment: 7 pages, 7 figures, accepted in Phys. Rev.
Formation of collective spins in frustrated clusters
Using magnetization, specific heat and neutron scattering measurements, as
well as exact calculations on realistic models, the magnetic properties of the
\lacuvo compound are characterized on a wide temperature range. At high
temperature, this oxide is well described by strongly correlated atomic =1/2
spins while decreasing the temperature it switches to a set of weakly
interacting and randomly distributed entangled pseudo spins and
. These pseudo-spins are built over frustrated clusters, similar to
the kagom\'e building block, at the vertices of a triangular superlattice, the
geometrical frustration intervening then at different scales.Comment: 10 page
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