Lattice and magnetic instabilities in Cu3Bi(SeO3)2O2X (X=Br, Cl)статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 9 ноября 2017 г.
Аннотация:Specific heat C, thermal conductivity κ, dielectric permittivity ε, electric polarization P, and Raman scattering experiments are performed on Cu3Bi(SeO3)2O2X (X=Br,Cl) single crystals. The Cl compound undergoes a structural phase transition at T∗∼115K evident in C(T), ɛ(T), and κ(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 TN∼25K marked by sharp λ-type singularities. For T<TN, 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.