Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Interfaces provide new control over oxides' electronic properties

Provided/Kyle Shen
An artist's rendering of a transition metal oxide superlattice, with an actual transmission electron microscopy image superimposed on the left panel. The red is manganese, yellow is lanthanum and blue is strontium. The top is a Fermi surface map which illustrates how electrons move in the material.
Provided/Kyle Shen

An artist's rendering of a transition metal oxide superlattice, with an actual transmission electron microscopy image superimposed on the left panel. The red is manganese, yellow is lanthanum and blue is strontium. The top is a Fermi surface map which illustrates how electrons move in the material.

Abstract:
Materials called transition metal oxides have physicists intrigued by their potentially useful properties -- from magnetoresistance (the reason a hard drive can write memory) to superconductivity.

Interfaces provide new control over oxides' electronic properties

Ithaca, NY | Posted on September 4th, 2012

By combining two sophisticated experimental tools -- oxide molecular beam expitaxy and angle-resolved photoemission spectroscopy -- researchers have gained the first insights into quantum interactions in transition metal oxide superlattices, which are artificial stacked layers of alternating materials, each just a few atoms thick.

Even slight modifications to the stacking sequence can switch the entire superlattice from a conductive to insulating state, due to the enhancement of quantum interactions between the electrons. The findings were published online Aug. 19 in the journal Nature Materials.

"We are interested in superlattices of transition metal oxides because they can exhibit all sorts of exotic electronic and magnetic properties that do not exist in the bulk of these materials," said Kyle Shen, assistant professor of physics and paper's senior author. "They might be useful someday, but from a scientific standpoint, they are just really fascinating because the electrons can conspire to give rise to very unexpected emergent phenomena."

For some transition metal oxide superlattices, it has been shown that adding just one extra layer of atoms to the stacked layers switches them from conductor to insulator. Shen and his colleagues wanted to understand why this occurs.

To do this, the team tapped the expertise of co-author Darrell Schlom, the Herbert Fisk Johnson Professor of Industrial Chemistry in the Department of Materials Science and Engineering, who with postdoctoral scholar Carolina Adamo, created specifically designed stacks of two oxides, lanthanum manganese oxide and strontium manganese oxide, each just a few atomic layers thick and with atomic precision. To make the superlattices, they used molecular beam epitaxy, which is like spray-painting with the elements of the periodic table.

The team then utilized a unique piece of instrumentation designed and built by Shen and Schlom's groups at Cornell. It allowed them to study the superlattices after synthesis by angle-resolved photoemission spectroscopy without exposing the surfaces to air, which would contaminate the sample and obscure the sensitive experiments. Eric Monkman, a graduate student in Shen's group, and colleagues then measured and analyzed how the electrons move through different kinds of superlattices.

It turned out that the distances between the interfaces of the lanthanum and strontium oxides were the key: Pushing the interfaces farther apart made the electrons more confined to each individual interface, resulting in an enhancement of the quantum interactions, which drive the entire superlattice into an insulating state.

By pushing the interfaces closer together, the electrons could start to move between interfaces, resulting in a metallic state. The researchers were able to reach these conclusions through the use of photoemission spectroscopy, which maps the motion of electrons in solids at the atomic scale.

Advanced transmission electron microscopy imaging led by David A. Muller, Cornell professor of applied and engineering physics and co-director of the Kavli Institute at Cornell for Nanoscale Science, and graduate student Julia Mundy, confirmed that the interfaces between the lanthanum and strontium were indeed sharp, which helped confirm the quantum interactions.

The paper's co-first authors are Monkman and Adamo. Shen, Schlom and Muller are members of the Kavli Institute at Cornell for Nanoscale Science. The research was supported by the National Science Foundation through the Cornell Center for Materials Research and a Career award.

####

For more information, please click here

Contacts:
Media Contact:
Syl Kacapyr
(607) 255-7701


Cornell Chronicle:
Anne Ju
(607) 255-9735

Copyright © Cornell University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Physics

A 'movie' of ultrafast rotating molecules at a hundred billion per second: A quantum wave-like nature was successfully observed in rotating nitrogen molecules July 4th, 2015

Clues to inner atomic life from subtle light-emission shifts: Hyperfine structure of light absorption by short-lived cadmium atom isotopes reveals characteristics of the nucleus that matter for high precision detection methods July 3rd, 2015

News and information

A 'movie' of ultrafast rotating molecules at a hundred billion per second: A quantum wave-like nature was successfully observed in rotating nitrogen molecules July 4th, 2015

New Biosensor Produced in Iran to Detect Effective Drugs in Cancer Treatment July 4th, 2015

Clues to inner atomic life from subtle light-emission shifts: Hyperfine structure of light absorption by short-lived cadmium atom isotopes reveals characteristics of the nucleus that matter for high precision detection methods July 3rd, 2015

Superconductivity

Making new materials with micro-explosions: ANU media release: Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon, the common computer chip material June 29th, 2015

Helium 'balloons' offer new path to control complex materials June 27th, 2015

Fabricating inexpensive, high-temp SQUIDs for future electronic devices June 22nd, 2015

Discovery paves way for new kinds of superconducting electronics June 22nd, 2015

Chip Technology

Nanometrics to Announce Second Quarter Financial Results on July 23, 2015 July 2nd, 2015

The quantum middle man July 2nd, 2015

New technology using silver may hold key to electronics advances July 2nd, 2015

Emergence of a 'devil's staircase' in a spin-valve system July 1st, 2015

Memory Technology

The quantum middle man July 2nd, 2015

Emergence of a 'devil's staircase' in a spin-valve system July 1st, 2015

Graphene flexes its electronic muscles: Rice-led researchers calculate electrical properties of carbon cones, other shapes June 30th, 2015

Buckle up for fast ionic conduction June 16th, 2015

Discoveries

A 'movie' of ultrafast rotating molecules at a hundred billion per second: A quantum wave-like nature was successfully observed in rotating nitrogen molecules July 4th, 2015

New Biosensor Produced in Iran to Detect Effective Drugs in Cancer Treatment July 4th, 2015

Clues to inner atomic life from subtle light-emission shifts: Hyperfine structure of light absorption by short-lived cadmium atom isotopes reveals characteristics of the nucleus that matter for high precision detection methods July 3rd, 2015

Groundbreaking research to help control liquids at micro and nano scales July 3rd, 2015

Announcements

A 'movie' of ultrafast rotating molecules at a hundred billion per second: A quantum wave-like nature was successfully observed in rotating nitrogen molecules July 4th, 2015

New Biosensor Produced in Iran to Detect Effective Drugs in Cancer Treatment July 4th, 2015

Clues to inner atomic life from subtle light-emission shifts: Hyperfine structure of light absorption by short-lived cadmium atom isotopes reveals characteristics of the nucleus that matter for high precision detection methods July 3rd, 2015

Pioneering Southampton scientist awarded prestigious physics medal July 3rd, 2015

Tools

A 'movie' of ultrafast rotating molecules at a hundred billion per second: A quantum wave-like nature was successfully observed in rotating nitrogen molecules July 4th, 2015

Clues to inner atomic life from subtle light-emission shifts: Hyperfine structure of light absorption by short-lived cadmium atom isotopes reveals characteristics of the nucleus that matter for high precision detection methods July 3rd, 2015

Nanometrics to Announce Second Quarter Financial Results on July 23, 2015 July 2nd, 2015

NIST ‘How-To’ Website Documents Procedures for Nano-EHS Research and Testing July 1st, 2015

Quantum nanoscience

A 'movie' of ultrafast rotating molecules at a hundred billion per second: A quantum wave-like nature was successfully observed in rotating nitrogen molecules July 4th, 2015

Freezing single atoms to absolute zero with microwaves brings quantum technology closer: Atoms frozen to absolute zero using microwaves July 2nd, 2015

The quantum spin Hall effect is a fundamental property of light June 25th, 2015

Lancaster University revolutionary quantum technology research receives funding boost June 22nd, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project