Quantum Paraelectricity To Dipolar Glass Transition In Sc Doped Bafe12o19 Single Crystals

We report a quantum paraelectric (QP) to dipolar glass (DG) phase transition induced by Sc substitution in ferrimagnetic hexaferrite BaFe12-xScxO19 (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 Sc3+ for Fe3+ in the bipyramids. Our results suggest further experimental clues to realize possible multiferroicity with strong displacive ferroelectricity in BaFe12O19 and other magnetic materials.