Hybrid Multiferroics beyond Geometric Ferroelectrics

From QCLab
Prof. Yoon Seok Oh (UNIST))
  • Speaker: Prof. Yoon Seok Oh (UNIST)
  • Date: Wednesday, January 18, 2017, at 17:00
  • Place: Jungho Seminar Room

Multiferroics are materials which have two or more order parameters in the same phase. Geometric ferroelectrics are called as improper ferroelectrics where geometric structural constraints, rather than typical cation-anion paring, induce ferroelectric polarization. Cross coupling between the geometric structural constraint and the electric polarization plays a key role to produce the polarization. Beyond the geometric ferroelectrics, hybrid ferroelectrics was theoretically predicted by the first principle calculations. In the hybrid ferroelectrics, trilinear coupling of three order parameters is main driving force to produce switchable electric polarization. However, due to complexity of the three order parameters’ cross coupling, existence of the hybrid ferroelectrics has been under debate. Recently, it has been experimentally demonstrated the trilinear coupling of three order parameters can produce switchable electric polarization. This successful demonstration proposes that the complex trilinear coupling of structure, magnetic, electric order parameters can be also main driving force to induce hybrid multiferroics at room temperature. In this seminar, I present our recent progress in order to find the hybrid multiferroics.