Integer and fractional quantum Hall effects in bilayer electron systems Original Research Article

Novel ferromagnetism in Ca1−xLaxB6 is studied in terms of the Ginzburg–Landau theory for excitonic order parameters, taking into account symmetry of the wavefunctions. We can predict a number of magnetic properties, i.e. antiferromagnetism and its magnetic structure, magneto-electric (ME) effect. They can be verified experimentally. This ME effect can also explain various novelties of the compound. Similarity with ferromagnetic CaB2C2 is also discussed.