83 research outputs found
Spontaneous Breaking of Isotropy Observed in the Electronic Transport of Rare-Earth Tritellurides
International audienceWe show that the isotropic conductivity in the normal state of rare-earth tritelluride RTe3 compounds is broken by the occurrence of theunidirectional charge density wave (CDW) in the (a, c) plane below the Peierls transition temperature. In contrast with quasi-one-dimensional systems, the resistivity anomaly associated with the CDW transition is strong in the direction perpendicular to the CDW wave vector Q (a axis) and very weak in the CDW wave vector Q direction (c axis). We qualitatively explain this result by calculating the electrical conductivity for the electron dispersion with momentum-dependent CDW gap as determined by angle-resolved photoemission spectroscopy. Similar measurements of in-plane conductivity may uncover the gap anisotropy in other compounds for which angle-resolved photoemission spectroscopy is not available
Spin liquid correlations in Nd-langasite anisotropic Kagom\'e antiferromagnet
Dynamical magnetic correlations in the geometrically frustrated
NdGaSiO compound were probed by inelastic neutron scattering
on a single crystal. A scattering signal with a ring shape distribution in
reciprocal space and unprecedented dispersive features was discovered.
Comparison with calculated static magnetic scattering from models of correlated
spins suggests that the observed phase is a spin liquid inherent to an
antiferromagnetic kagom\'e-like lattice of anisotropic Nd moments.Comment: 4 page
Magnetic order in the frustrated Ising-like chain compound SrNiIrO
We have studied the field and temperature dependence of the magnetization of
single crystals of Sr3NiIrO6. These measurements evidence the presence of an
easy axis of anisotropy and two anomalies in the magnetic susceptibility.
Neutron powder diffraction realized on a polycrystalline sample reveals the
emergence of magnetic reflections below 75 K with magnetic propagation vector k
~ (0, 0, 1), undetected in previous neutron studies [T.N. Nguyen and H.-C zur
Loye, J. Solid State Chem., 117, 300 (1995)]. The nature of the magnetic ground
state, and the presence of two anomalies common to this family of material, are
discussed on the basis of the results obtained by neutron diffraction,
magnetization measurements, and symmetry arguments
Parity Broken Chiral Spin Dynamics in BaNbFeSiO
The spin wave excitations emerging from the chiral helically modulated
120 magnetic order in a langasite BaNbFeSiO
enantiopure crystal were investigated by unpolarized and polarized inelastic
neutron scattering. A dynamical fingerprint of the chiral ground state is
obtained, singularized by (i) spectral weight asymmetries answerable to the
structural chirality and (ii) a full chirality of the spin correlations
observed over the whole energy spectrum. The intrinsic chiral nature of the
spin waves elementary excitations is shown in absence of macroscopic time
reversal symmetry breaking
THz Magneto-electric atomic rotations in the chiral compound BaNbFeSiO
We have determined the terahertz spectrum of the chiral langasite
BaNbFeSiO by means of synchrotron-radiation measurements.
Two excitations are revealed that are shown to have a different nature. The
first one, purely magnetic, is observed at low temperature in the magnetically
ordered phase and is assigned to a magnon. The second one persits far into the
paramagnetic phase and exhibits both an electric and a magnetic activity at
slightly different energies. This magnetoelectric excitation is interpreted in
terms of atomic rotations and requires a helical electric polarization
Further analysis of the quantum critical point of CeLaRuSi
New data on the spin dynamics and the magnetic order of
CeLaRuSi are presented. The importance of the Kondo
effect at the quantum critical point of this system is emphasized from the
behaviour of the relaxation rate at high temperature and from the variation of
the ordered moment with respect to the one of the N\'eel temperature for
various .Comment: Contribution for the Festschrift on the occasion of Hilbert von
Loehneysen 60 th birthday. To be published as a special issue in the Journal
of Low Temperature Physic
NRT2.1 phosphorylation prevents root high affinity nitrate uptake activity in Arabidopsis thaliana
In Arabidopsis thaliana, NRT2.1 codes for a main component of the root nitrate high-affinity transport system. Previous studies revealed that post-translational regulation of NRT2.1 plays an important role in the control of root nitrate uptake and that one mechanism could correspond to NRT2.1 C-terminus processing. To further investigate this hypothesis, we produced transgenic plants with truncated forms of NRT2.1. It revealed an essential sequence for NRT2.1 activity, located between the residues 494-513. Using a phospho-proteomic approach, we found that this sequence contains one phosphorylation site, at serine 501, which can inactivate NRT2.1 function when mimicking the constitutive phosphorylation of this residue in transgenic plants. This phenotype could neither be explained by changes in abundance of NRT2.1 and NAR2.1, a partner protein of NRT2.1, nor by a lack of interaction between these two proteins. Finally, the relative level of serine 501 phosphorylation was found to be modulated by nitrate in wildtype plants. Altogether, these observations allowed us to propose a model for a new and essential mechanism for the regulation of NRT2.1 activity
Helical bunching and symmetry lowering inducing multiferroicity in Fe langasites
International audienceThe chiral Fe-based langasites represent model systems of triangle-based frustrated magnets with a strong potential for multiferroicity. We report neutron scattering measurements for the multichiral Ba3MFe3Si2O14 (M = Nb, Ta) langasites revealing new important features of the magnetic order of these systems: the bunching of the helical modulation along the c-axis and the in-plane distortion of the 120° Fe-spin arrangement. We discuss these subtle features in terms of the microscopic spin Hamiltonian, and provide the link to the magnetically-induced electric polarization observed in these systems. Thus, our findings put the multiferroicity of this attractive family of materials on solid ground
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