SciPost Commentary Page
|Title:||Chirality and orbital order in charge density waves|
|Author(s):||Jasper van Wezel|
|As Contributors:||Jasper van Wezel|
|Journal ref.:||EPL (Europhysics Letters) 96, 67011|
Helical arrangements of spins are common among magnetic materials. The ﬁrst material to harbor a corkscrew pattern of charge density, on the other hand, was discovered only very recently. The nature of the order parameter is of key relevance, since rotating a magnetic vector around any propagation vector trivially yields a helical pattern. In contrast, the purely scalar charge density cannot straightforwardly support a chiral state. Here we use a Landau order parameter analysis to resolve this paradox, and show that the chiral charge order may be understood as a form of orbital ordering. We discuss the microscopic mechanism driving the transition and show it to be of a general form, thus allowing for a broad class of materials to display this novel type of orbital-ordered chiral charge density wave.