Featured Research

from universities, journals, and other organizations

New Property Found In Ancient Mineral Lodestone

Date:
December 18, 2007
Source:
Rice University
Summary:
Using the latest nanofabrication methods, physicists have discovered a surprising new electronic property in one of the earliest-known and most-studied magnetic minerals on Earth -- lodestone. Also known as magnetite, lodestone was used to make compass needles as early as 900 years ago. The researchers describe how super-cooled magnetite reverted from an insulator to a conductor when the voltage was altered in their experiment.

Using the latest methods for nanofabrication, a team led by Rice University physicists has discovered a surprising new electronic property in one of the earliest-known and most-studied magnetic minerals on Earth -- lodestone, also known as magnetite.

By changing the voltage in their experiment, researchers were able to get magnetite at temperatures colder than minus 250 degrees Fahrenheit to revert from an insulator to a conductor.

"It's fascinating that we can still find surprises in a material like magnetite that has been studied for thousands of years," said lead researcher Doug Natelson, associate professor of physics and astronomy. "This kind of finding is really a testament to what's possible now that we can fabricate electronic devices to study materials at the nanoscale."

The magnetic properties of lodestone, also known as magnetite, were documented in China more than 2,000 years ago, and Chinese sailors were navigating with lodestone compasses as early as 900 years ago.

Magnetite is a particular mineral of iron oxide. Its atoms are arranged in a crystal structure with four oxygen atoms for every three of iron, and their arrangement gives the mineral its characteristic magnetic and electrical properties. Physicists have known for more than 60 years that the electronic properties of magnetite change radically and quickly at cold temperatures. As the material cools below a critical temperature near minus 250 degrees Fahrenheit, it changes from an electrical conductor to an electrical insulator -- a electrical transformation that's akin to the physical change water undergoes when it freezes into ice.

"When we applied a sufficiently large voltage across our nanostructures we found that we could kick the cooled magnetite out of its insulating phase and cause it to become a conductor again," Natelson said. "The transition is very sharp, and when the voltage is then lowered back below a lower critical value the magnetite snaps back into its insulating phase. We don't know exactly why this switching occurs, but we think further experiments will shed light on this and the nature of the insulating state."

With engineers looking to exploit novel electronic materials for next-generation computers and hard drives, phase transitions between insulating and conducting states have become an increasingly hot research topic in physics and materials science in recent years.

The debate about the causes and specifics of magnetite's temperature-driven phase change has simmered much longer. Natelson said physicists have long sparred about the possible underlying physical and electronic causes of the phase transition. The discovery of this new voltage-driven switching provides new clues, but more research is still needed, he said.

"The effect we discovered probably wasn't noticed in the past because nanotechnology is only now making it possible to prepare the electrodes, nanoparticles, and thin films required for study with the precision necessary to document the effect," he said.

Natelson's team experimented on two kinds of magnetite. One, called nanorust, consists of tiny particles of magnetite developed in the laboratory of Rice chemist Vicki Colvin, director of Rice's Center for Biological and Environmental Nanotechnology. The second, thin films of single-crystal magnetite, were produced by Igor Shvets' research group at the University of Dublin's Trinity College. These high quality materials with precise compositions were essential to the study, said Natelson.

The research was published online Dec. 16 and will be included in February's print edition of Nature Materials. The research was funded by the Department of Energy.


Story Source:

The above story is based on materials provided by Rice University. Note: Materials may be edited for content and length.


Cite This Page:

Rice University. "New Property Found In Ancient Mineral Lodestone." ScienceDaily. ScienceDaily, 18 December 2007. <www.sciencedaily.com/releases/2007/12/071217173315.htm>.
Rice University. (2007, December 18). New Property Found In Ancient Mineral Lodestone. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2007/12/071217173315.htm
Rice University. "New Property Found In Ancient Mineral Lodestone." ScienceDaily. www.sciencedaily.com/releases/2007/12/071217173315.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) — TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) — Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) — When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) — 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:  

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile iPhone Android Web
          Follow Facebook Twitter Google+
          Subscribe RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins