A strong ferroelectric ferromagnet created by means of spin–lattice coupling

Multiferroics made easier Ferroelectric ferromagnets, or multiferroics, are of significant technological interest because they combine the low power and high speed of field-effect electronics with the permanence and routability of voltage-controlled ferromagnetism. Unfortunately, they are rare, and those that do exist have ferroelectric and ferromagnetic properties that are typically weak compared with conventional useful ferroelectrics and ferromagnets. A new route to fabricating multiferroics was recently predicted: in theory, magnetically ordered insulators that are neither ferroelectric nor ferromagnetic — of which there are many — can be turned into ferroelectric multiferroics by strain from the underlying substrate. June Hyuk Lee et al . now realize this route experimentally for EuTiO3. Their demonstration that a single experimental parameter, strain, can simultaneously control multiple order parameters opens up exciting possibilities for creating useful multiferroic materials. Ferroelectric ferromagnets — materials that are both ferroelectric and ferromagnetic — are of significant technological interest. But they are rare, and those that do exist have weak ferroelectric and ferromagnetic properties. Recently a new way of fabricating such materials was proposed, involving strain from the underlying substrate. This route has now been realized experimentally for EuTiO 3 . The work shows that a single experimental parameter, strain, can simultaneously control multiple order parameters. Ferroelectric ferromagnets are exceedingly rare, fundamentally interesting multiferroic materials that could give rise to new technologies in which the low power and high speed of field-effect electronics are combined with the permanence and routability of voltage-controlled ferromagnetism 1 , 2 . Furthermore, the properties of the few compounds that simultaneously exhibit these phenomena 1 , 2 , 3 , 4 , 5 are insignificant in comparison with those of useful ferroelectrics or ferromagnets: their spontaneous polarizations or magnetizations are smaller by a factor of 1,000 or more. The same holds for magnetic- or electric-field-induced multiferroics 6 , 7 , 8 . Owing to the weak properties of single-phase multiferroics, composite and multilayer approaches involving strain-coupled piezoelectric and magnetostrictive components are the closest to application today 1 , 2 . Recently, however, a new route to ferroelectric ferromagnets was proposed 9 by which magnetically ordered