Theory of Excitonic States in CaB6

Abstract

We study the excitonic states in CaB6 in terms of the Ginzburg-Landau theory. By minimizing the free energy and by comparing with experimental results, we identify two possible ground states with exciton condensation. They both break time-reversal and inversion symmetries. This leads to various magnetic and optical properties. As for magnetic properties, it is expected to be an antiferromagnet, and its spin structure is predicted. It will exhibit the magnetoelectric effect, and observed novel ferromagnetism in doped samples and in thin-film and powder samples can arise from this effect. Interesting optical phenomena such as the nonreciprocal optical effect and the second harmonic generation are predicted. Their measurement for CaB6 will clarify whether exciton condensation occurs or not and which of the two states is realized.

17 pages, 3 figures

References in corpus (6)

• Point defects, ferromagnetism and transport in calcium hexaboride
• Bulk Band Gaps in Divalent Hexaborides
• Fermi Surface Measurements on the Low Carrier Density Ferromagnet Ca1-xLaxB6 and SrB6
• Theory of Ferromagnetism in Doped Excitonic Condensates
• Weak Ferromagnetism and Excitonic Condensates
• Theory of Ferromagnetism in Ca1-xLaxB6

Cited by in corpus (7)

• Optical Magnetoelectric Effect in Multiferroic Materials: Evidence for a Lorentz Force Acting on a Ray of Light
• Excitonic condensation in systems of strongly correlated electrons
• Electronic Structure of Calcium Hexaboride within the Weighted Density Approximation
• Gigantic Enhancement of Magneto-Chiral Effect in Photonic Crystals
• ARPES insights on the metallic states of YbB6(001): E(k) dispersion, temporal changes and spatial variation
• Optical spectroscopy study on the electronic structure of $E{u}_{1-x}C{a}_x{B}_6$
• Scaling of the largest dynamical barrier in the one-dimensional long-range Ising spin-glass