1. Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
2. Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573, Japan
3. Present address: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

Correspondence to: T. Kimura^1,3 Email: tkimura@lanl.gov

Abstract

The magnetoelectric effect—the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field—was first presumed to exist by Pierre Curie¹, and subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2–4). More recently, related studies on magnetic ferroelectrics^{5, 6, 7, 8, 9, 10, 11, 12, 13, 14} have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility¹⁵, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO₃, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO₃, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media.