Magnetic and Dielectric Properties of RbCoBr_3 Inspected from Nonmagnetic Impurity Effect(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

概要

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Through magnetic and dielectric measurements, a simultaneous phase transition of spin and lattice systems observed previously at 37.2K of RbCoBr_3 have been investigated by doping with nonmagnetic Mg impurities. A mutual reduction in the ferroelectric Curie temperature T_c and the Neel temperature T_N due to the enhancement of Mg doping confirms the occurrence of the synergistic ordering of both. A broad peak of the real part of dielectric constant along the c axis, ⋴'_c(T), at approximately 32K of the pure system splits into two sharp peaks in mixed systems. This suggests the presence of successive structural phase transitions at around this temperature. A probable sequence of crystal and magnetic structures was discussed for the successive phase transitions of RbCo_<1-x>Mg_xBr_3. The interplay between the spin and lattice variables of RbCoBr_3 was interpreted by taking account of spin-dependent polarizability and spin-dependent spontaneous polarization. A dielectric anomaly observed at 9.0K in RbCoBr_3, where &isins'_c (T) has a sharp peak, was ascribed to the occurrence of another structural transition.
社団法人日本物理学会の論文
2006-09-15