Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > A Deeper Look at Interfaces: Researchers at Berkeley Lab’s Advanced Light Source Develop New Technique for Probing Subsurface Electronic Structure

Experimental setup and basic principles of SWARPES shows (a) the experimental setup; (b) diagram of the multilayer STO and LSMO film; (c) SW-excited photoemission intensity rocking curves and (d) simulated intensity of the x-ray standing wave field as a function of depth and grazing incidence angle.
Experimental setup and basic principles of SWARPES shows (a) the experimental setup; (b) diagram of the multilayer STO and LSMO film; (c) SW-excited photoemission intensity rocking curves and (d) simulated intensity of the x-ray standing wave field as a function of depth and grazing incidence angle.

Abstract:
"The interface is the device," Nobel laureate Herbert Kroemer famously observed, referring to the remarkable properties to be found at the junctures where layers of different materials meet. In today's burgeoning world of nanotechnology, the interfaces between layers of metal oxides are becoming increasingly prominent, with applications in such high-tech favorites as spintronics, high-temperature superconductors, ferroelectrics and multiferroics. Realizing the vast potential of these metal oxide interfaces, especially those buried in subsurface layers, will require detailed knowledge of their electronic structure.

A Deeper Look at Interfaces: Researchers at Berkeley Lab’s Advanced Light Source Develop New Technique for Probing Subsurface Electronic Structure

Berkeley, CA | Posted on January 15th, 2014

A new technique from an international team of researchers working at Berkeley Lab's Advanced Light Source (ALS) promises to deliver the goods. In a study led by Charles Fadley, a physicist who holds joint appointments with Berkeley Lab's Materials Sciences Division and the University of California Davis, where he is a Distinguished Professor of Physics, the team combined two well-established techniques for studying electronic structure in crystalline materials into a new technique that is optimized for examining electronic properties at subsurface interfaces. They call this new technique SWARPES, for Standing Wave Angle-Resolved Photoemission Spectroscopy.

"SWARPES allows us for the first time to selectively study buried interfaces with either soft or hard x-rays," Fadley says. "The technique can be applied to any multilayer prototype device structure in spintronics, strongly correlated/high-TC superconductors, or semiconductor electronics. The only limitations are that the sample has to have a high degree of crystalline order, and has to be grown on a nanoscale multilayer mirror suitable for generating an x-ray standing wave."

As the name indicates, SWARPES combines the use of standing waves of x-rays with ARPES, the technique of choice for studying electronic structure. A standing wave is a vibrational pattern created when two waves of identical wavelength interfere with one another: one is the incident x-ray and the other is the x-ray reflected by a mirror. Interactions between standing waves and core-level electrons reveal much about the properties of each atomic species in a sample. ARPES from the outer valence levels is the long-standing spectroscopic workhorse for the study of electronic structure. X-rays striking a material surface or interface cause the photoemission of electrons at angles and kinetic energies that can be measured to obtain detailed electronic energy levels of the sample. While an extremely powerful tool, ARPES, a soft x-ray technique, is primarily limited to the study of near-surface atoms. It's harder x-ray cousin, HARPES, makes use of more energetic x-rays to effectively probe subsurface interfaces, but the addition of the standing wave capability provides a much desired depth selectivity.

"The standing wave can be moved up and down in a sample simply by rocking the angle of incidence around the Bragg angle of the mirror," says Alexander Gray, a former member of Fadley's UC Davis research group and affiliate with Berkeley Lab's Materials Sciences Division, who is now a postdoctoral associate at Stanford/SLAC. "Observing an interface between a ferromagnetic conductor (lanthanum strontium manganite) and an insulator (strontium titanate), which constitute a magnetic tunnel junction used in spintronic logic circuits, we've shown that changes in the electronic structure can be reliably measured, and that these changes are semi-quantitatively predicted by theory at several levels. Our results point to a much wider use of SWARPES in the future for studying the electronic properties of buried interfaces of many different kinds."

Fadley, Gray and their collaborators carried out their SWARPES tests at ALS Beamline 7.0.1. The Advanced Light Source is a U.S. Department of Energy (DOE) national user facility and Beamline 7.0.1 features a premier endstation for determining the electronic structure of metals, semiconductors and insulators. Additional corroborating measurements concerning the interface atomic structure were performed at the National Center for Electron Microscopy (NCEM), another DOE national user facility hosted at Berkeley Lab.

This research was supported primarily by the U.S. Department of Energy (DOE) Office of Science.

####

For more information, please click here

Contacts:
Lynn Yarris

510-486-5375

Copyright © Berkeley Lab

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 Links

Results of this study have been published in Europhysics Letters (EPL). The paper is titled “Momentum-resolved electronic structure at a buried interface from soft X-ray standing-wave angle-resolved photoemission.” Gray was the lead author, Fadley the corresponding author. For a full list of co-authors and their host institutes download the paper here:

For more about the research of Charles Fadley, go here:

For more about Berkeley Lab’s Advanced Light Source go here:

For more about NCEM go here:

Related News Press

Superconductivity

Superconductor could be realized in a broken Lorenz invariant theory July 7th, 2015

News and information

Superconductor could be realized in a broken Lorenz invariant theory July 7th, 2015

New technique enables magnetic patterns to be mapped in 3-D July 7th, 2015

Crystal structure and magnetism -- new insight into the fundamentals of solid state physics: HZB team decodes relationship between magnetic interactions and the distortions in crystal structure within a geometrically 'frustrated' spinel system July 7th, 2015

Down to the quantum dot: Jülich researchers develop ultrahigh-resolution 3-D microscopy technique for electric fields July 7th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Could black phosphorus be the next silicon? New material could make it possible to pack more transistors on a chip, research suggests July 7th, 2015

A cool way to form 2-D conducting polymers using ice: POSTECH scientists develop breakthrough technique to easily optimize electrical properties of Polyaniline nanosheets to an unprecedented level in an environmental-friendly and inexpensive way July 7th, 2015

New technique enables magnetic patterns to be mapped in 3-D July 7th, 2015

Surfing a wake of light: Researchers observe and control light wakes for the first time July 6th, 2015

Spintronics

Fundamental observation of spin-controlled electrical conduction in metals: Ultrafast terahertz spectroscopy yields direct insight into the building block of modern magnetic memories July 6th, 2015

Influential Interfaces Lead to Advances in Organic Spintronics July 1st, 2015

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

Spintronics advance brings wafer-scale quantum devices closer to reality June 24th, 2015

Chip Technology

Could black phosphorus be the next silicon? New material could make it possible to pack more transistors on a chip, research suggests July 7th, 2015

A cool way to form 2-D conducting polymers using ice: POSTECH scientists develop breakthrough technique to easily optimize electrical properties of Polyaniline nanosheets to an unprecedented level in an environmental-friendly and inexpensive way July 7th, 2015

Fundamental observation of spin-controlled electrical conduction in metals: Ultrafast terahertz spectroscopy yields direct insight into the building block of modern magnetic memories July 6th, 2015

Transition from 3 to 2 dimensions increases conduction, MIPT scientists discover July 6th, 2015

Discoveries

Superconductor could be realized in a broken Lorenz invariant theory July 7th, 2015

New technique enables magnetic patterns to be mapped in 3-D July 7th, 2015

Crystal structure and magnetism -- new insight into the fundamentals of solid state physics: HZB team decodes relationship between magnetic interactions and the distortions in crystal structure within a geometrically 'frustrated' spinel system July 7th, 2015

Down to the quantum dot: Jülich researchers develop ultrahigh-resolution 3-D microscopy technique for electric fields July 7th, 2015

Materials/Metamaterials

BBC World Service to broadcast Forum discussion on graphene July 6th, 2015

Production of Zirconium Carbide Nanoparticles at Low Temperature without Thermal Operations July 5th, 2015

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

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

Announcements

Superconductor could be realized in a broken Lorenz invariant theory July 7th, 2015

New technique enables magnetic patterns to be mapped in 3-D July 7th, 2015

Crystal structure and magnetism -- new insight into the fundamentals of solid state physics: HZB team decodes relationship between magnetic interactions and the distortions in crystal structure within a geometrically 'frustrated' spinel system July 7th, 2015

Down to the quantum dot: Jülich researchers develop ultrahigh-resolution 3-D microscopy technique for electric fields July 7th, 2015

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Could black phosphorus be the next silicon? New material could make it possible to pack more transistors on a chip, research suggests July 7th, 2015

Superconductor could be realized in a broken Lorenz invariant theory July 7th, 2015

New technique enables magnetic patterns to be mapped in 3-D July 7th, 2015

Crystal structure and magnetism -- new insight into the fundamentals of solid state physics: HZB team decodes relationship between magnetic interactions and the distortions in crystal structure within a geometrically 'frustrated' spinel system July 7th, 2015

Tools

Evident Thermoelectrics Announces Launch of World's-First Thermoelectric Product Based on Skutterudite Material Technology July 7th, 2015

Expert presentations and practical demonstrations impress nanoparticle characterization seminar attendees July 7th, 2015

New technique enables magnetic patterns to be mapped in 3-D July 7th, 2015

Down to the quantum dot: Jülich researchers develop ultrahigh-resolution 3-D microscopy technique for electric fields July 7th, 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