Superlattice design realizes elusive multiferroic properties

August 21, 2015 by Amanda Morris
Superlattice structure of lithium osmate and lithium niobate

From the spinning disc of a computer's hard drive to the varying current in a transformer, many technological devices work by merging electricity and magnetism. But the search to find a single material that combines both electric polarizations and magnetizations remains challenging.

This elusive class of materials is called , which combine two or more primary ferroic properties. Northwestern University's James Rondinelli and his research team are interested in combining ferromagnetism and ferroelectricity, which rarely coexist in one material at .

"Researchers have spent the past decade or more trying to find materials that exhibit these properties," said Rondinelli, assistant professor of materials science and engineering at Northwestern's McCormick School of Engineering. "If such materials can be found, they are both interesting from a fundamental perspective and yet even more attractive for technological applications."

In order for ferroelectricity to exist, the material must be insulating. For this reason, nearly every approach to date has focused on searching for multiferroics in insulating magnetic oxides. Rondinelli's team started with a different approach. They instead used quantum mechanical calculations to study a metallic oxide, lithium osmate, with a structural disposition to and sandwiched it between an , .

While lithium osmate is a non-magnetic and non-insulating metal, lithium niobate is insulating and ferroelectric but also non-magnetic. By alternating the two materials, Rondinelli created a superlattice that—at the quantum scale—became insulating, ferromagnetic, and ferroelectric at room temperature.

"The polar metal became insulating through an electronic phase transition," Rondinelli explained. "Owing to the physics of the enhanced electron-electron interactions in the superlattice, the electronic transition induces an ordered magnetic state."

Supported by the Army Research Office and the US Department of Defense, the research appears in the August 21 issue of Physical Review Letters. Danilo Puggioni, a postdoctoral fellow in Rondinelli's lab, is the paper's first author, who is joined by collaborators at the International School for Advanced Studies in Trieste, Italy.

This new design strategy for realizing multiferroics could open up new possibilities for electronics, including logic processing and new types of memory storage. Multiferroic also hold potential for low-power electronics as they offer the possibility to control magnetic polarizations with an electric field, which consumes much less energy.

"Our work has turned the paradigm upside down," Rondinelli said. "We show that you can start with metallic oxides to make multiferroics."

Explore further: Ferroelectric oxides do the twist

More information: Design of a Mott Multiferroic from a Nonmagnetic Polar Metal, dx.doi.org/10.1103/PhysRevLett.115.087202

Related Stories

Ferroelectric oxides do the twist

April 12, 2012

(Phys.org) -- Some materials, by their nature, do what we want them to do -- notably, the ubiquitous, semiconducting silicon found in almost every electronic device. But sometimes, naturally occurring materials need a little ...

Researchers open path to finding rare, polarized metals

April 2, 2014

Drexel University researchers are turning some of the basic tenets of chemistry and physics upside down to cut a trail toward the discovery of a new set of materials. They're called "polar metals" and, according to many of ...

Multiferroics could lead to low-power devices

May 17, 2011

(PhysOrg.com) -- Magnetic materials in which the north and south poles can be reversed with an electric field may be ideal candidates for low-power electronic devices, such as those used for ultra-high data storage. But finding ...

Recommended for you

Studying the quantum vacuum: Traffic jam in empty space

January 18, 2017

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by Professor Alfred Leitenstorfer has now shown how to manipulate the ...

Flexible ferroelectrics bring two material worlds together

January 17, 2017

Until recently, "flexible ferroelectrics" could have been thought of as the same type of oxymoronic phrase. However, thanks to a new discovery by the U.S. Department of Energy's (DOE) Argonne National Laboratory in collaboration ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.