Researchers suggest new memory storage mineral

Jan 21, 2010 By Anne Ju
A representation of the mineral kotoite's crystal structure. The oxygen atoms are red, and the magnesium atoms are located at the centers of the green octahedra. The boron atoms are located at the centers of the blue triangles connecting the oxygen atoms. Image: Derek Stewart

( -- Researcher Derek Stewart says the mineral kotoite could be an ideal insulator for memory storage devices called magnetic tunnel junctions.

Breakthroughs in electronics often are the result of finding just the right material for a device -- like the tungsten in light bulbs or the silicon in transistors. Now, a Cornell scientist believes that the mineral kotoite could be an ideal insulator for devices called magnetic tunnel junctions, found in computers, cell phones and magnetic field sensors.

The work, building on previous research by other Cornell scientists, is published by Derek Stewart, the Cornell NanoScale Science and Technology Facility's computational research associate, in the Dec. 17 online edition of (to appear later in print).

Magnetic tunnel junctions are made of a sandwich of two magnets, typically iron-based, with an oxide in the middle only nanometers thick. Electrons "tunnel" between the two magnets, and the oxide filters information from the electrons' spin states to create what is called nonvolatile memory, which doesn't require electricity to store information. These junctions are also used as very sensitive magnetic sensors or read heads for hard drives, since the device currents depend on the relative orientation of the iron layers' .

Cornell researchers, including Robert Buhrman, the John Edson Sweet Professor of Engineering, and Dan Ralph, the Horace White Professor of Physics, have been on the leading edge of this technology for several years.

In industry today, most magnetic tunnel junctions use as the insulator. But in labs across the world, magnesium oxide is being tested as a next-generation insulator, because its cubic crystal structure matches well with the metallic leads, allowing more efficient filtering of electrons. John Read, a former graduate student in Buhrman's lab (now a postdoctoral associate at the National Institute of Standards and Technology), discovered by accident that the element boron, which he had used at Cornell while fabricating magnetic tunnel junctions to help smooth the material interfaces, was leaking into the insulators and forming a crystal, rather than diffusing away as intended. Yet the devices still worked.

Curious, the team tapped Stewart's computational expertise to work backward and figure out what specific material may have been inadvertently created between the two magnets as a result of the boron contamination.

Density functional calculations brought Stewart to kotoite (Mg3B2O6), a magnesium oxide that also has two boron atoms, which matches well with the magnets' chemistry, allows good electron filtering, and has a slightly different crystal shape than plain magnesium oxide (MgO). He also demonstrated that the mineral's crystal shape -- orthorhombic, as opposed to magnesium oxide's cubic symmetry -- could lead to even better electron spin filtering.

"Derek did a beautiful job of demonstrating that the symmetry arguments that one makes for can be demonstrated for [kotoite]," Read said.

Explore further: Thinnest feasible nano-membrane produced

Related Stories

Electric control of aligned spins improves computer memory

Jan 19, 2010

Researchers from Helmholtz-Zentrum Berlin (HZB, Germany) and the French research facility CNRS, south of Paris, are using electric fields to manipulate the property of electrons known as "spin" to store data permanently. ...

Tunneling Across a Ferroelectric

Jul 14, 2006

University of Nebraska-Lincoln physicist Evgeny Tsymbal's groundbreaking identification of an emerging research field in electronic devices earned publication this week in Science magazine.

New Nanoparticle Structure Boosts Magnetic Properties

Dec 19, 2005

Magnetic nanoparticles have shown promise as contrast-enhancing agents for improving cancer detection using magnetic resonance imaging (MRI), as miniaturized heaters capable of killing malignant cells, and as targeted drug ...

Novel Zigzag Shape Gives Sensors Magnetic Appeal

Jan 05, 2005

Scientists at the National Institute of Standards and Technology (NIST) have designed tiny magnetic sensors in a "zigzag" shape that are simpler in design and likely will be cheaper to make than conventional ...

Physicist develops battery using new source of energy

Mar 11, 2009

Researchers at the University of Miami and at the Universities of Tokyo and Tohoku, Japan, have been able to prove the existence of a "spin battery," a battery that is "charged" by applying a large magnetic ...

Recommended for you

Thinnest feasible nano-membrane produced

Apr 17, 2014

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Apr 17, 2014

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

( —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

User comments : 0

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...