Researchers create, manipulate new multiferroic materials

October 22, 2009 – A team of researchers from the US have created a new multiferroic material possessing seemingly contradictory properties of magnetism and polar order, and another group of scientists from the US and the Netherlands say they can control suchmultiferroic properties — achievements that have implications in future electronics and particularly memory devices.

Magnetic ferroelectrics could be used as magnetic switches (by reversing their electric fields) in future memory, sensors, actuators, and multifunction devices. Through their work, researchers from Argonne National Labs, Penn State U., the U. of Chicago, and Cornell U. proved a high-pressure form of polycrystalline FETiO3 possesses the unusual combination of weak ferromagnetism (below 120 Kelvin) and ferroelectric polarization (at and below room temperature). Results, published in July by Physical Review Letters, were obtained by using piezoresponse force microscopy, optical second harmonic generation, and magnetometry. Funding for their research was provided by the US Department of Energy.

Meanwhile, researchers from the U. of Twente, Oakridge National Labs, U. of California/Berkeley, and Penn State say they have used an electrical signal to control both the elastic and magnetic properties of such a nanomaterial "in an orderly way," opening up new possibilities for storage devices with very high data densities.

Their work, published online by Nature Nanotechnology, applied an electrical voltage to the needle of a scanning probe microscopy and moved it over the surface of a bismuth ferrate (BiFeO3) structure to "charge" it with different elastic and magnetic properties "at a very localized level."

From their paper abstract:

The ability to control local elastic, magnetic, and torroidal order parameters with an electric field will make it possible to probe local strain and magnetic ordering, and engineer various magnetoelectric, domain-wall-based, and strain-coupled devices.


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Manipulation of the polarization in nanostructures: (a) an artificial star, (b) a diamond pattern. (Source: U. of Twente)



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