Novel magnetic semiconductor puts new spin on electronics

May 24, 2006

Researchers at MIT's Francis Bitter Magnet Lab have developed a novel magnetic semiconductor that may greatly increase the computing power and flexibility of future electronic devices while dramatically reducing their power consumption. The work was reported in the April issue of Nature Materials.

The new material is a significant step forward in the field of spin-based electronics -- or "spintronics" -- where the spin state of electrons is exploited to carry, manipulate and store information. Conventional electronic circuits use only the charge state (current on or off) of an electron, but these tiny particles also have a spin direction (up or down).

Devices such as laptops and iPods already employ spintronics to store information in their super-high-capacity magnetic hard drives, but using electron spin states to process information through circuits would be a dramatic advance in computing. "We can carry information in two ways at once, and this will allow us to further reduce the size of electronic circuits," says Jagadeesh Moodera, a senior research scientist at the Magnet Lab and leader of the research team. Today's circuits carry information by varying the on/off state of current passed through electrons. Those same electrons could carry additional information through their spin orientation.

The magnetic semiconductor material created by Moodera's team is indium oxide with a small amount of chromium added. It sits on top of a conventional silicon semiconductor, where it injects electrons of a given spin orientation into the semiconductor. The spin-polarized electrons then travel through the semiconductor and are read by a spin detector at the other end of the circuit.

Although the new material is promising in itself, Moodera says the real breakthrough is their demonstration that the material's magnetic behavior depends on defects, or missing atoms (vacancies), in a periodic arrangement of atoms. This cause-and-effect relationship was uncertain before, but Moodera's team was able to tune the material's magnetic behavior over a wide range by controlling defects at the atomic level.

"This is what has been missing all along," he says. "The beauty of it is that our work not only shows this magnetic semiconductor is real, but also technologically very useful."

The new material's ability to inject spin at room temperature and its compatibility with silicon make it particularly useful. Its optical transparency means it also could find applications in solar cells and touch panel circuitry, according to Moodera.

In addition to reducing circuit size, spintronics could create more versatile devices because electron spins can be changed reversibly (from up to down and vice versa) along circuits using an electrode gate. "We currently have multifunctional cellphones, for example, that act as phones, cameras and music players," says Moodera. "Spintronics could create even greater multifunctionality in the future."

Spintronics may also reduce the power consumption of information devices. Spin states are considered "nonvolatile," meaning they retain stored information even when the power is switched off -- this is why magnetic hard drives hold information without power. Spin electronics could create circuits that operate similarly, storing and passing information without the need for a continuous current to retain the data. "In such a system, we can transmit spin information without moving charges," says Moodera. "It's like creating a ripple in a pond -- it travels all the way across without adding more energy."

Source: Massachusetts Institute of Technology

Explore further: Technique simplifies the creation of high-tech crystals

add to favorites email to friend print save as pdf

Related Stories

A new multi-bit 'spin' for MRAM storage

Jul 22, 2014

Interest in magnetic random access memory (MRAM) is escalating, thanks to demand for fast, low-cost, nonvolatile, low-consumption, secure memory devices. MRAM, which relies on manipulating the magnetization ...

Earth-crushing pressure? This electron spin doesn't care

Jul 09, 2014

(Phys.org) —To fully understand something, it is often instructive to view it at its extremes. How do materials behave when their bits are forced much closer together than is comfortable? How do electrons ...

The quantum dance of oxygen

Jul 07, 2014

Under extremely high pressure conditions oxygen molecules group into quartets and give rise to a 'dance of their magnetic moments.' This, as observed in a new study carried out by SISSA in collaboration with ...

From pencil marks to quantum computers

Jul 03, 2014

Pick up a pencil. Make a mark on a piece of paper. Congratulations: you are doing cutting-edge condensed matter physics. You might even be making the first mark on the road to quantum computers, according ...

Recommended for you

New approach to form non-equilibrium structures

6 hours ago

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

7 hours ago

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

Unleashing the power of quantum dot triplets

11 hours ago

Quantum computers have yet to materialise. Yet, scientists are making progress in devising suitable means of making such computers faster. One such approach relies on quantum dots—a kind of artificial atom, ...

Chemist develops X-ray vision for quality assurance

12 hours ago

It is seldom sufficient to read the declaration of contents if you need to know precisely what substances a product contains. In fact, to do this you need to be a highly skilled chemist or to have genuine ...

The future of ultrashort laser pulses

12 hours ago

Rapid advances in techniques for the creation of ultra-short laser pulses promise to boost our knowledge of electron motions to an unprecedented level.

User comments : 0