Quantum paraelectricity to dipolar glass transition in Sc doped BaFe 12 O 19 single crystals

Abstract

We report a quantum paraelectric (QP) to dipolar glass (DG) phase transition induced by Sc substitution in ferrimagnetic hexaferrite BaFe 12 - x Sc x O 19 (0 ≤ x ≤ 2.4) single crystals. The DG behavior is revealed via anisotropic dielectric spectroscopy, polarization, and specific heat measurements. The phase evolution from QP to DG (0.5 ≤ x ≤ 1.2) and finally to the nonpolar state (x ≥ 2.4) with increasing x is found to be due to the competition between the enhanced polar instability by lattice volume expansion and disordered/frustrated dipole-dipole interaction induced by the partial replacement of Sc 3 + for Fe 3 + in the bipyramids. Our results suggest further experimental clues to realize possible multiferroicity with strong displacive ferroelectricity in BaFe 12 O 19 and other magnetic materials.