41 research outputs found
Quantum and thermal ionic motion, oxygen isotope effect, and superexchange distribution in La<sub>2</sub>CuO<sub>4</sub>
We study the zero-point and thermal ionic motion in LaCuO by means of
high-resolution neutron diffraction experiments. Our results demonstrate
anisotropic motion of O and to a lesser extent of Cu ions, both consistent with
the structure of coupled CuO octahedra, and quantify the relative effects
of zero-point and thermal contributions to ionic motion. By substitution of
O, we find that the oxygen isotope effect on the lattice dimensions is
small and negative (), while the isotope effect on the ionic
displacement parameters is significant ( to ). We use our results as
input for theoretical estimates of the distribution of magnetic interaction
parameters, , in an effective one-band model for the cuprate plane. We find
that ionic motion causes only small () effects on the average value
, which vary with temperature and O isotope, but results in
dramatic (-) fluctuations in values that are subject to
significant (-) isotope effects. We demonstrate that this motional
broadening of can have substantial effects on certain electronic and
magnetic properties in cuprates.Comment: 13 pages, 9 figure
Thoracoscopy guided by intraoperative indocyanine green fluorescence lymphography for post-oesophagectomy chylothorax (with video)
International audienc
Oesogastric anastomosis technique by thoracoscopy in prone position during Ivor Lewis procedure (with video)
International audienc
Résection colorectale cœlioscopique chez une patiente avec stomie pour occlusion sur endométriose
International audienc
Difficult hemostasis during rectal resection
International audienc
Low frequency acoustic radiation of cylindrical shells in water
International audienc