Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

News and information

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Artificial photosynthesis steps into the light: Rice University lab turns transition metals into practical catalyst for solar, other applications March 23rd, 2017

Superconductivity

Electro-optical switch transmits data at record-low temperatures: Operating at temperatures near absolute zero, switch could enable significantly faster data processing with lower power consumption March 20th, 2017

Discovery in new material raises questions about theoretical models of superconductivity March 13th, 2017

Research reveals novel quantum state in strange insulating materials February 14th, 2017

Physics

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

Research reveals novel quantum state in strange insulating materials February 14th, 2017

Sorting machine for atoms:Researchers at the University of Bonn clear a further hurdle on the path to creating quantum computers February 10th, 2017

Chip Technology

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Scientists discover new 'boat' form of promising semiconductor: GeSe Uncommon form attenuates semiconductor's band gap size March 23rd, 2017

Pulverizing e-waste is green, clean -- and cold: Rice, Indian Institute researchers use cryo-mill to turn circuit boards into separated powders March 21st, 2017

Electro-optical switch transmits data at record-low temperatures: Operating at temperatures near absolute zero, switch could enable significantly faster data processing with lower power consumption March 20th, 2017

Memory Technology

Smart multi-layered magnetic material acts as an electric switch: New study reveals characteristic of islands of magnetic metals between vacuum gaps, displaying tunnelling electric current March 1st, 2017

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Research opens door to smaller, cheaper, more agile communications tech February 16th, 2017

Scientists determine precise 3-D location, identity of all 23,000 atoms in a nanoparticle: Berkeley Lab researchers help to map iron-platinum particle in unprecedented detail February 6th, 2017

Discoveries

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Artificial photosynthesis steps into the light: Rice University lab turns transition metals into practical catalyst for solar, other applications March 23rd, 2017

Announcements

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Artificial photosynthesis steps into the light: Rice University lab turns transition metals into practical catalyst for solar, other applications March 23rd, 2017

Tools

Cryo-electron microscopy achieves unprecedented resolution using new computational methods March 25th, 2017

Caught on camera -- chemical reactions 'filmed' at the single-molecule level March 22nd, 2017

CRMGroup in Belgium uses a Deben three point bending stage in the development of new steel & coated steel products for automotive and other industrial applications March 21st, 2017

Next-gen steel under the microscope March 18th, 2017

Quantum nanoscience

The speed limit for intra-chip communications in microprocessors of the future January 23rd, 2017

First experimental proof of a 70 year old physics theory: First observation of magnetic phase transition in 2-D materials, as predicted by the Nobel winner Onsager in 1943 January 6th, 2017

Quantum simulation technique yields topological soliton state in SSH model January 3rd, 2017

Diamonds are technologists' best friends: Researchers from the Lomonosov Moscow State University have grown needle- and thread-like diamonds and studied their useful properties December 30th, 2016

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