Realization of Giant Magnetoelectricity in Helimagnets

Abstract

We show that low field magnetoelectric (ME) properties of helimagnets Ba0.5Sr1.5Zn2(Fe1-xAlx)(12)O-22 can be efficiently tailored by the Al-substitution level. As x increases, the critical magnetic field for switching electric polarization is systematically reduced from similar to 1 T down to similar to 1 mT, and the ME susceptibility is greatly enhanced to reach a giant value of 2.0 x 10(4) ps/m at an optimum x = 0.08. We find that control of the nontrivial orbital moment in the octahedral Fe sites through the Al substitution is crucial for fine-tuning the magnetic anisotropy and obtaining the conspicuously improved ME characteristics.