arXiv subjects

Marie-Hélène Lemée-Cailleau

Publications and source records attributed to Marie-Hélène Lemée-Cailleau.

3 recordsLinked to original sources

arXiv2017

Evolution of the partially frustrated magnetic order in CePd$_{1-x}$Ni$_x$Al

We report on a single-crystal neutron diffraction study of the evolution of the antiferromagnetic order in the heavy-fermion compound CePd$_{1-x}$Ni$_x$Al which exhibits partial geometric frustration due to its distorted Kagomé structure. The magnetic structure is found to be unchanged with a propagation vector $Q_\mathrm{AF} \approx (0.5~0~0.35)$ for all Ni concentrations $x$ up to $x_c \approx 0.14$. Upon approaching the quantum critical concentration $x_c$, the ordered moment vanishes linearly with Néel temperature $T_{\rm N}$, in good agreement with CePdAl under hydrostatic pressure. For all Ni concentrations, substantial short-range magnetic correlations are observed above $T_{\rm N}$ as a result of frustration.

cond-mat.str-el↗

arXiv2014

Magnetic structures of non-cerium analogues of heavy-fermion Ce2RhIn8: case of Nd2RhIn8, Dy2RhIn8 and Er2RhIn8

R2RhIn8 compounds (space group P4/mmm, R is a rare-earth element) belong to a large group of structurally related tetragonal materials which involves several heavy-fermion superconductors based on Ce. We have succeeded to grow single crystals of compounds with Nd, Dy and Er and following our previous bulk measurements, we performed neutron-diffraction studies to determine their magnetic structures. The Laue diffraction experiment showed that the antiferromagnetic order below the Néel temperature is in all three compounds characterized by the propagation vector k = (1/2, 1/2, 1/2). The amplitude and direction of the magnetic moments, as well as the invariance symmetry of the magnetic structure, were determined by subsequent experiments using two- and four-circle diffractometers. The critical exponents were determined from the temperature dependence of the intensities below TN.

cond-mat.supr-con↗

arXiv2007

Anomalous dispersion of optical phonons at the neutral-ionic transition: Evidence from diffuse X-ray scattering

Diffuse X-ray data for mixed stack organic charge-transfer crystals approaching the neutral-ionic phase transition can be quantitatively explained as due to the softening of the optical phonon branch. The interpretation is fully consistent with vibrational spectra, and underlines the importance of electron-phonon coupling in low-dimensional systems with delocalized electrons.

cond-mat.str-el↗