Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Navy Scientists Demonstrate Breakthrough in Tunnel Barrier Technology

Diagram (left) of the graphene-based magnetic tunnel junction, where a single atom thick layer of carbon atoms in a honeycomb lattice separates two magnetic metal films (cobalt and permalloy). The magnetizations of the films can be aligned parallel or antiparallel, resulting in a change in resistance for current flowing through the structure, called the tunnel magnetoresistance (TMR). The plot (right) shows the TMR as an applied magnetic field changes the relative orientation of the magnetizations  the TMR persists well above room temperature.
(U.S. Naval Research Laboratory)
Diagram (left) of the graphene-based magnetic tunnel junction, where a single atom thick layer of carbon atoms in a honeycomb lattice separates two magnetic metal films (cobalt and permalloy). The magnetizations of the films can be aligned parallel or antiparallel, resulting in a change in resistance for current flowing through the structure, called the tunnel magnetoresistance (TMR). The plot (right) shows the TMR as an applied magnetic field changes the relative orientation of the magnetizations the TMR persists well above room temperature.

(U.S. Naval Research Laboratory)

Abstract:
Scientists at the Naval Research Laboratory have demonstrated, for the first time, the use of graphene as a tunnel barrier an electrically insulating barrier between two conducting materials through which electrons tunnel quantum mechanically. They report fabrication of magnetic tunnel junctions using graphene, a single atom thick sheet of carbon atoms arranged in a honeycomb lattice, between two ferromagnetic metal layers in a fully scalable photolithographic process. Their results demonstrate that single-layer graphene can function as an effective tunnel barrier for both charge and spin-based devices, and enable realization of more complex graphene-based devices for highly functional nanoscale circuits, such as tunnel transistors, non-volatile magnetic memory and reprogrammable spin logic. These research results are published in the online issue of Nano Letters (14 May 2012; DOI: 10.1021/nl3007616).

Navy Scientists Demonstrate Breakthrough in Tunnel Barrier Technology

Washington, DC | Posted on July 31st, 2012

The research initiates a "paradigm shift in tunnel barrier technology for magnetic tunnel junctions (MTJs) used for advanced sensors, memory and logic," explains NRL's Dr. Berend Jonker. Graphene has been the focus of intense research activity because of its remarkable electronic and mechanical properties. In the past, researchers focused on developing graphene as a conductor, or perhaps a semiconductor, where the current flows in-plane parallel to the carbon honeycomb sheet. In contrast, the NRL researchers show that graphene serves as an excellent tunnel barrier when current is directed perpendicular to the plane, and in fact, also preserves the spin polarization of the tunneling current.

Tunnel barriers are the basis for many electronic (charge-based) and spintronic (spin-based) device structures. Fabrication of ultra-thin and defect-free barriers is an ongoing challenge in materials science. Typical tunnel barriers are based on metal oxides (e.g. aluminum oxide or magnesium oxide), and issues such as non-uniform thicknesses, pinholes, defects and trapped charge compromise their performance and reliability. Such oxide tunnel barriers have several limitations which hinder future performance. For example, they have high resistance-area (RA) products which results in higher power consumption and local heating; they allow interdiffusion at the interfaces, which reduces their performance and can lead to catastrophic failure; and their thickness is generally non-uniform, resulting in "hot spots" in the current transport. In contrast, Dr. Jonker explains, the inherent material properties of graphene make it an ideal tunnel barrier. Graphene is chemically inert and impervious to diffusion even at high temperatures. The atomic thickness of graphene represents the ultimate in tunnel barrier scaling for the lowest possible RA product, lowest power consumption and fastest switching speed.

This discovery by NRL researchers is significant because MTJs are widely utilized as read heads in the hard disk drive found in every computer, and as memory elements in non-volatile magnetic random access memory (MRAM) which is rapidly emerging as a universal memory replacement for the many varieties of conventional semiconductor-based memory. They are also considered to be lead contenders as reprogrammable, non-volatile elements for a universal logic block.

Although there has been significant progress, the emerging generation of MTJ-based MRAM relies upon spin-transfer torque switching, and is severely limited by the unacceptably high current densities required to switch the logic state of the cell. The accompanying issues of power consumption and thermal dissipation prevent scaling to higher densities and operation at typical CMOS voltages. The 2011 International Technology Roadmap for Semiconductors (ITRS) states that "all of the existing forms of nonvolatile memory face limitations based on material properties. Success will hinge on finding and developing alternative materials and/or developing alternative emerging technologies ... development of electrically accessible non-volatile memory with high speed and high density would initiate a revolution in computer architecture ... and provide a significant increase in information throughput beyond the traditional benefits of scaling when fully realized for nanoscale CMOS devices" (ITRS 2011 Executive Summary, p28; and Emerging Research Devices, p. 4).

NRL researchers believe that the graphene-based magnetic tunnel junctions they have demonstrated will eclipse the performance and ease of fabrication of existing oxide technology. These graphene-based MTJs would be a breakthrough for nascent spin-based technologies like MRAM and spin logic, and enable the electrically accessible non-volatile memory required to initiate a revolution in computer architecture. These results also pave the way for utilization of other two-dimensional materials such as hexagonal boron nitride for similar applications.

The NRL research team includes Dr. Enrique Cobas, Dr. Adam Friedman, Dr. Olaf van 't Erve, and Dr. Berend Jonker from the Materials Science and Technology Division, and Dr. Jeremy Robinson from the Electronics Science and Technology Division.

####

About U.S. Naval Research Laboratory
The U.S. Naval Research Laboratory is the Navy's full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 85 years and continues to meet the complex technological challenges of today's world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.

For more information, please click here

Contacts:
The NRL Public Affairs Office
202-767-2541

Copyright © U.S. Naval Research Laboratory

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

NRL homepage

Related News Press

Laboratories

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

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

Researchers develop groundbreaking process for creating ultra-selective separation membranes: Discovery could greatly improve energy-efficiency of separation and purification processes in the chemical and petrochemical industries March 15th, 2017

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

Perovskite edges can be tuned for optoelectronic performance: Layered 2D material improves efficiency for solar cells and LEDs March 10th, 2017

Graphene/ Graphite

Intertronics introduce new nanoparticle deagglomeration technology March 15th, 2017

Space energy technology restored to make power stations more efficient: Scientists use graphene to reinvent abandoned heat energy converter technology March 7th, 2017

Openings/New facilities/Groundbreaking/Expansion

GLOBALFOUNDRIES Expands to Meet Worldwide Customer Demand: Company invests for capacity growth in the United States, Germany, China and Singapore February 10th, 2017

Portable superconductivity systems for small motors: Cambridge University lab achieves a breakthrough for portable superconductivity systems that are applicable for small motors, health care and other uses February 8th, 2017

New Agricultural Research Center Debuts at UCF October 12th, 2016

Nexeon Establishes Base in Asia October 11th, 2016

Govt.-Legislation/Regulation/Funding/Policy

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

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

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

Chip Technology

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

ATTOPSEMI Technology Joins FDXcelerator Program to Deliver Advanced Non-Volatile Memory IP to GLOBALFOUNDRIES 22 FDX Technology Platform: Leading-edge I-fuse brings higher reliability, smaller cell size and ease of programmability for consumer, automotive, and IoT applications March 27th, 2017

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

Memory Technology

Information storage with a nanoscale twist: Discovery of a novel rotational force inside magnetic vortices makes it easier to design ultrahigh capacity disk drives March 28th, 2017

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

Discoveries

Information storage with a nanoscale twist: Discovery of a novel rotational force inside magnetic vortices makes it easier to design ultrahigh capacity disk drives March 28th, 2017

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

Researchers make flexible glass for tiny medical devices: Glass can bend over and over again on a nanoscale March 27th, 2017

Announcements

Information storage with a nanoscale twist: Discovery of a novel rotational force inside magnetic vortices makes it easier to design ultrahigh capacity disk drives March 28th, 2017

ATTOPSEMI Technology Joins FDXcelerator Program to Deliver Advanced Non-Volatile Memory IP to GLOBALFOUNDRIES 22 FDX Technology Platform: Leading-edge I-fuse brings higher reliability, smaller cell size and ease of programmability for consumer, automotive, and IoT applications March 27th, 2017

Leti and HORIBA Scientific to Host Webinar on Ultrafast Characterization Tool: Plasma Profiling Time-of-Flight Mass Spectrometer Tool Cuts Optimization Time In Layer Deposition and Fabrication of Wide Range of Applications March 27th, 2017

Laser activated gold pyramids could deliver drugs, DNA into cells without harm: Microstructures create temporary pores in cells March 27th, 2017

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