Cooperative Jahn-Teller effect on the X-ray diffraction spectra in DyBC

Nagao, Tatsuya*; Igarashi, Junichi

To investigate the effect of the lattice distortion on the resonant X-ray scattering (RXS) spectra in DyBC, we study the crystal electric field Hamiltonian to fit the low-lying level scheme. By using the quasi-quartet ground states of the Hamiltonian, we analyze the cooperative Jahn-Teller effect at absolute zero. We find that a certain type of buckling of sheets of B and C atoms is an energetically favored state. This naturally leads to a canted quadrupole ordering phase consistent with the experiment. We show that the obtained lattice distortion gives rise to large intensities on RXS spectra around the Dy L edge by modulating 5d bands.