Lattice and magnetic instabilities in Cu3Bi(SeO3)(2)O2X (X = Br, Cl)

Article

关键词: CRYSTAL-STRUCTURE;    FRANCISITE;   

DOI  :  10.1103/PhysRevB.96.115144

来源: SCIE

【 摘 要 】

Specific heat C, thermal conductivity kappa, dielectric permittivity epsilon, electric polarization P, and Raman scattering experiments are performed on Cu3Bi(SeO3)(2)O2X (X = Br, Cl) single crystals. The Cl compound undergoes a structural phase transition at T * similar to 115K evident in C(T), epsilon(T), and kappa(T) and accompanied by the appearance of unique phonon lines in Raman scattering. No evident structural changes are detected in the Br compound. At T < T*, a very weak polarization loop with a P || c axis is observed in the Cl compound. Both compounds order antiferromagnetically at comparable temperatures T-N similar to 25K marked by sharp lambda-type singularities. For T < T-N, an intensive mode of magnetic origin appears in both compounds. At the lowest temperatures, the energy of this mode is in good agreement with both the magnon excitation observed in infrared spectroscopy and the spin gap found recently in inelastic neutron scattering of the Cl compound.

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