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C Lhuillier

Publications and source records attributed to C Lhuillier.

16 recordsLinked to original sources
PubMed2005

Two-step restoration of SU(2) symmetry in a frustrated ring-exchange magnet.

We demonstrate the existence of a spin-nematic, moment-free phase in a quantum four-spin ring-exchange model on the square lattice. This unusual quantum state is created by the interplay of frustration and quantum fluctuations that lead to a partial restoration of SU(2) symmetry when going from a four-sublattice orthogonal biaxial Néel order to this exotic uniaxial magnet. A further increase of frustration drives a transition to a fully gapped SU(2) symmetric valence bond crystal.

Journal Article↗
PubMed2002

Numerical simulation of transit-time ultrasonic flowmeters: uncertainties due to flow profile and fluid turbulence.

Flowmeter measurement using the ultrasonic transit-time method is based on the apparent difference of the sound velocity in the flow direction and in the opposite direction. This method gives a flow velocity averaged along a particular acoustical path. To convert this path velocity to a velocity averaged over the entire cross-section of the flowing medium, the knowledge of the flow velocity profile is essential. However, the acoustical paths joining the two transducers are supposed to be straight and fluid turbulence phenomena are neglected. In this paper, we describe a numerical procedure to estimate the uncertainties due to these approximations in the case of fully developed turbulence. The ultrasonic propagation is modelled in 2-D moving inhomogeneous media via a ray tracing algorithm. Influence of mean profiles of temperature and velocity is studied on simple examples. Fluid temperature fluctuations and fluid velocity turbulence are considered in the stochastic framework to obtain average uncertainties on the measurements of the liquid flow rate.

Journal Article↗
PubMed2000

Magnetothermodynamics of the spin- 1 / 2 Kagome antiferromagnet

In this paper, we use a new hybrid method to compute the thermodynamic behavior of the spin- 1 / 2 Kagome antiferromagnet under the influence of a large external magnetic field. We find a T2 low-temperature behavior and a very low sensitivity of the specific heat to a strong external magnetic field. We display clear evidence that this low-temperature magnetothermal effect is associated with the existence of low-lying fluctuating singlets, but also that the whole picture ( T2 behavior of C(v) and the thermally activated spin susceptibility) implies contribution of both nonmagnetic and magnetic excitations. Comparison with experiments is made.

Journal Article↗
PubMed1990

[Which approach should be chosen for inverted nasosinusal papilloma?].

Inverted papillomas are a benign tumors arising from the external wall of the nasal cavity. Sinus extension is easy to evaluate pre-operatively by using the CT-scan. Lateral rhinotomy is therefore not the only way to removing these tumors. Vestibular and endonasal approaches can be considered. Surgical treatment must however remove the tumor tissue completely since recurrence results directly from insufficiency and must be completed by an histological analysis of the whole tissue after its removal in view of its frequent association with carcinoma.

Humans↗