2018/03/27 by Makoto Naka, Eriko Mizoguchi, Joji Nasu +1
Materials Science · Physics and Astronomy · #Dielectric #Ferroelectric and Piezoelectric Materials #Ferroelectricity #Hamiltonian (control theory) #Magnetoelectric effect #Multiferroics #Multiferroics and related materials #Phase transition #Polarization (electrochemistry) #Polarization density #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.7566/jpsj.87.063709
5 pages, 4 figures
arxiv created 2018/03/27 · openalex created_date 2018/04/06 · openalex publication_date 2018/05/25 · arxiv updated 2018/06/13 · openalex updated_date 2026/08/05
Magnetic, dielectric, and magnetoelectric properties in a spin-state transition system are examined, motivated by the recent discovery of a multiferroic behavior in a cobalt oxide. We construct an effective model Hamiltonian based on the two-orbital Hubbard model, in which the spin-state degrees of freedom in magnetic ions couple with ferroelectric-type lattice distortions. A phase transition occurs from the high-temperature low-spin phase to the low-temperature high-spin ferroelectric phase with accompanying an increase of the spin entropy. The calculated results are consistent with the experimental pressure-temperature phase diagram. We predict the magnetic-field induced electric polarization in the low-spin paraelectric phase near the ferroelectric phase boundary.