Navigation Links
New property found in ancient mineral lodestone
Date:12/17/2007

HOUSTON -- Dec. 17, 2007 -- 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. The research was published online Dec. 16 and will be included in February's print edition of Nature Materials.

"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.


'/>"/>

Contact: B.J. Almond
balmond@rice.edu
713-348-6770
Rice University
Source:Eurekalert

Related biology technology :

1. Angiotech receives favourable patent decision from New Zealands Intellectual Property Office
2. Amyris Biotechnologies Co-Founder Neil Renninger Named to Technology Reviews Prestigious TR35 List of Top Young Innovators
3. PDL BioPharma Announces Internal CEO Investigation Found No Credible Evidence of Improper Personal Conduct or Breach of Fiduciary Duty
4. GeneGo and the Cystic Fibrosis Foundation Collaborate to Advance Understanding of Cystic Fibrosis
5. More Than 230 Cyclists to Ride in Amgen California Coast Classic Bike Tour to Raise $1.3 Million for Arthritis Foundation
6. Founder of ILEX Oncology and Triton Biosciences, Richard Love, Joins Board of Directors of Cell Therapeutics, Inc. (CTI)
7. Medivation Selected as Founding Member of New NASDAQ(R) NeuroInsights(R) Neurotech Index
8. International Atomic Energy Agency and National Foundation for Cancer Research Launch Major Initiative to Improve Cancer Prevention and Treatments in Developing Countries
9. Ikaria Founding Scientist Named 2007 MacArthur Fellow
10. Melanoma Research Foundation and Seattle Cancer Care Alliance Host Educational Symposium and Reception for Melanoma Patients, Family Members and Healthcare Providers
11. Foundation for Biomedical Research Board Chairman Awarded Congressional Gold Medal
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/11/2017)... LAGUNA HILLS, Calif. , Oct. 11, 2017 ... London (ICR) and University of ... prognostic tool to risk-stratify patients with multiple myeloma (MM), in ... nine . The University of Leeds ... by Myeloma UK, and ICR will perform the testing services ...
(Date:10/10/2017)... CA (PRWEB) , ... October ... ... a development-stage cancer-focused pharmaceutical company advancing targeted antibody-drug conjugate (ADC) therapeutics, today ... of targeted HPLN (Hybrid Polymerized Liposomal Nanoparticle), a technology developed in collaboration ...
(Date:10/10/2017)... ... October 10, 2017 , ... ... process optimization firm for the life sciences and healthcare industries, announces a presentation ... San Francisco. , The presentation, “Automating GxP Validation for Agile Cloud Platforms,” will ...
(Date:10/9/2017)... ... October 09, 2017 , ... The Giving Tree ... products targeting the needs of consumers who are incorporating medical marijuana into their ... Phoenix, Arizona. , As operators of two successful Valley dispensaries, The Giving Tree’s ...
Breaking Biology Technology:
(Date:3/29/2017)... March 29, 2017  higi, the health IT company ... North America , today announced a Series ... acquisition of EveryMove. The new investment and acquisition accelerates ... tools to transform population health activities through the collection ... higi collects and secures data today on ...
(Date:3/24/2017)... The Controller General of Immigration from Maldives Mr. Mohamed Anwar ... the prestigious international IAIR Award for the most innovative high security ePassport ... ... Maldives Immigration Controller General, Mr. ... on the right) have received the IAIR award for the "Most innovative ...
(Date:3/23/2017)... Research and Markets has announced the addition of the ... to 2025" report to their offering. ... The Global Vehicle Anti-Theft System Market ... the next decade to reach approximately $14.21 billion by 2025. ... for all the given segments on global as well as regional ...
Breaking Biology News(10 mins):