Seeing is believing: negative capacitance captured at both nano-and macro-scales

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2019,（6）
• 页码范围: 361-363
• 页数: 3页
• 语种: 英文

摘要

The phenomenological theory of ferroelectrics was developed by Landau-Devonshire about 70years ago in the 1940s [1],and the celebrated theory has been very successful in analyzing ferroelectric phase transitions [2,3],domain structures [4],as well as strain engineering [5,6].Recently,it has been demonstrated that it is also capable of capturing emerging polarization textures such as a ferroelectric vortex [7],proving its wide applicability not only at phenomenological level,but also at the atomic scale.The idea is simple,that the internal energy density of a ferroelectric depends on polarization,the order parameter,and upon the phase transition,the energy becomes degenerate,corresponding to multiple ferroelectric variants arising from broken symmetry.Such behavior is captured well by a polynomial of polarization with temperaturedependent coefficient,as Devonshire originally demonstrated for barium titanate [1].