Publications associées à Groupe ponctuel de symétrie

Diversity of radial spin textures in chiral materials

Oleg Yazyev, Daniel Gosalbez Martinez, Alberto Crepaldi

We introduce a classification of the radial spin textures in momentum space that emerge at the high-symmetry points in crystals characterized by nonpolar chiral point groups (D2, D3, D4, D6, T, O). Based on the symmetry constraints imposed by these point g ...

Amer Physical Soc2023

Shear and Breathing Modes of Layered Materials

Nicola Marzari, Giovanni Pizzi, Marco Gibertini

Layered materials (LMs), such as graphite, hexagonal boron nitride, and transition-metal dichalcogenides, are at the center of an ever-increasing research effort, due to their scientific and technological relevance. Raman and infrared spectroscopies are ac ...

AMER CHEMICAL SOC2021

Quantum spin liquid phases in the bilinear-biquadratic two-SU(4)-fermion Hamiltonian on the square lattice

Olivier Clément Romain Gauthé

We consider the phase diagram of the most general SU(4)-symmetric two-site Hamiltonian for a system of two fermions per site (i.e., self-conjugate 6 representation) on the square lattice. It is known that this model hosts magnetic phases breaking SU(4) sym ...

AMER PHYSICAL SOC2020

Icosahedral quasicrystal-enhanced nucleation of the fcc phase in liquid gold alloys

Michel Rappaz, Güven Kurtuldu, Alberto Sicco

Although the grain refinement of yellow gold alloys with Jr has been used in industry and known for nearly half a century, the basic mechanism is still unknown. The present contribution shows that the mechanism is the same as that evidenced recently in Al- ...

Elsevier2014

Analysing Friedel averages and differences

Philip Pattison

Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to ...

International Union of Crystallography2012

Closing Large Hyperbolic 2g-gons : a Way to Study Hyperelliptic Riemann Surfaces of Genus g

Poincaré's uniformisation theorem says that any Riemann surface is conformally equivalent to a unique (up to isometry) surface of constant Gauss curvature 0, 1 or –1. The (topologically) richest of these three worlds is for curvature –1 formed of hyperboli ...

EPFL2012

Intertwining of Zeeman and Coulomb interactions on excitons in highly symmetric semiconductor quantum dots

Daniel Oberli

We present an experimental study and develop a group theoretical analysis of the Zeeman effect on excitons in pyramidal semiconductor quantum dots possessing the symmetries of the C3v point group. The magnetic field dependence of the emission pattern origi ...

2012

Differential geometry: a natural tool for describing symmetry operations

Gervais Chapuis, Kurt Schenk, Philippe Kocian

Differential geometry provides a useful mathematical framework for describing the fundamental concepts in crystallography. The notions of point and associated vector spaces correspond to those of manifold and tangent space at a given point. A space-group o ...

International Union of Crystallography2009

Inducibility of Drug-metabolizing Enzymes by Xenobiotics in Mice with Liver-specific Knockout of Ctnnb1

Jörg Hülsken, Massimiliano Schwarz

Basal as well as xenobiotic-induced expression of the main enzymes from phase I and phase II of drug metabolism is confined to the perivenous areas of the mammalian liver lobule. Whereas signal transduction pathways that govern xenobiotic-induced expressio ...

2009

Mechanical spectroscopy of interface stress relaxation in magnesium matrix composites

Abu Salek Md. Fahim Chowdhury

Magnesium matrix composites made of pure (99.98%) magnesium reinforced with long carbon (Mg/C) and stainless steel (Mg/steel) fibers were processed by low pressure infiltration method. Mg/C composites were then oriented from the crystallographic point of v ...

EPFL2009