CHONG-DER HU2018-09-102018-09-10201010980121http://www.scopus.com/inward/record.url?eid=2-s2.0-77956319532&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/357630We proposed that in multiferroics, there exists a third long-range order besides the electric polarization and magnetic order. This long-range order reduces the symmetry of the spatial part of the wave functions of electrons. Thus the cancellation in the "spin-current" model can be avoided. As a result, the expectation value of electric polarization will be larger by an order of magnitude. We have derived a distinct form of electric polarization P- ∼- × ( sj ×sj+1), where Q- is the wave vector of this long-range order. © 2010 The American Physical Society.[SDGs]SDG7journal article10.1103/PhysRevB.81.2244142-s2.0-77956319532WOS:000278482500005