Chirality and orbital order in charge density waves
Materials Science Division, Argonne National Laboratory - Argonne, IL 60439, USA
Accepted: 10 November 2011
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.
PACS: 71.45.Lr – Charge-density-wave systems / 11.30.Rd – Chiral symmetries / 71.30.+h – Metal-insulator transitions and other electronic transitions
© EPLA, 2011