Thermodynamic approach to electric quadrupole moments
Akito Daido, Atsuo Shitade, Youichi Yanase
Abstract
Higher-rank electric/magnetic multipole moments are attracting attention these days as candidate order parameters for exotic material phases. However, the quantum mechanical formulation of those multipole moments is still an ongoing issue. In this paper, we propose a thermodynamic definition of electric quadrupole moments as a measure of symmetry breaking, following previous studies of orbital magnetic dipole moments and magnetic quadrupole moments. The obtained formulas are illustrated with a model of orbital-ordered nematic phases of iron-based superconductors.
Topics & Concepts
Multipole expansionQuadrupoleMagnetic dipoleMagnetic momentDipoleCondensed matter physicsPhysicsSymmetry (geometry)Quadrupole magnetElectron magnetic dipole momentCumulantQuantum mechanicsMathematicsGeometryStatisticsIron-based superconductors researchAdvanced Condensed Matter PhysicsRare-earth and actinide compounds