Science Current Events | Science News |

Nano-layer of ruthenium stabilizes magnetic sensors

August 06, 2007
A layer of ruthenium just a few atoms thick can be used to fine-tune the sensitivity and enhance the reliability of magnetic sensors, tests at the National Institute of Standards and Technology (NIST) show.* The nonmagnetic metal acts as a buffer between active layers of sensor materials, offering a simple means of customizing field instruments such as compasses, and stabilizing the magnetization in a given direction in devices such as computer hard-disk readers.

In the NIST sensor design, ruthenium modulates interactions between a ferromagnetic film (in which electron "spins" all point in the same direction) and an antiferromagnetic film (in which different layers of electrons point in opposite directions to stabilize the device). In the presence of a magnetic field, the electron spins in the ferromagnetic film rotate, changing the sensor's resistance and producing a voltage output. The antiferromagnetic film, which feels no force because it has no net magnetization, acts like a very stiff spring that resists the rotation and stabilizes the sensor. The ruthenium layer (see graphic) is added to weaken the spring, effectively making the device more sensitive. This makes it easier to rotate the electron spins, and still pulls them back to their original direction when the field is removed.

NIST tests showed that thicker buffers of ruthenium (up to 2 nanometers) make it easier to rotate the magnetization of the ferromagnetic film, resulting in a more sensitive device. Thinner buffers result in a device that is less sensitive but responds to a wider range of external fields. Ruthenium layers thicker than 2 nm prevent any coupling between the two active films. All buffer thicknesses from 0 to 2 nm maintain sensor magnetization (even resetting it if necessary) without a boost from an external electrical current or magnetic field. This easily prevents demagnetization and failure of a sensor.

The mass-producible test sensors, made in the NIST clean room in Boulder, Colo., consist of three basic layers of material deposited on silicon wafers: The bottom antiferromagnetic layer is 8 nm of an iridium/manganese alloy, followed by the ruthenium buffer, and topped with 25 nm of a nickel/iron alloy. The design requires no extra lithography steps for the magnetic layers and could be implemented in existing mass-production processes. By contrast, the conventional method of modulating magnetoresistive sensors-capping the ends of sensors with magnetic materials-adds fabrication steps and does not allow fine-tuning of sensitivity. The new sensor design was key to NIST's recent development of a high-resolution forensic tape analysis system for the Federal Bureau of Investigation (see Magnetic Tape Analysis "Sees" Tampering in Detail).

* S.T. Halloran, F.C. da Silva, H.Z. Fardi and D.P. Pappas. Permanent-magnet-free stabilization and sensitivity tailoring of magneto-resistive field sensors, Journal of Applied Physics. August 1, 2007.

National Institute of Standards and Technology (NIST)

Related Ruthenium Current Events and Ruthenium News Articles

Stinging nettle chemical improves cancer drug
A cancer drug could be made 50 times more effective by a chemical found in stinging nettles and ants, new research finds.

First scientific publication from data collected at NSLS-II
Just weeks after the National Synchrotron Light Source II (NSLS-II), a U.S. Department of Energy Office of Science User Facility at Brookhaven National Laboratory, achieved first light, a team of scientists at the X-Ray Powder Diffraction (XPD) beamline tested a setup that yielded data on thermoelectric materials.

Transformations of diazo compounds catalyzed by environmentally benign iron complexes
Catalysis can be used to enhance the reactivity and selectivity of specific chemical transformations and decrease the amount of energy consumed by these processes.

Batteries included: A solar cell that stores its own power
Is it a solar cell? Or a rechargeable battery? Actually, the patent-pending device invented at The Ohio State University is both: the world's first solar battery.

How to make a 'perfect' solar absorber
The key to creating a material that would be ideal for converting solar energy to heat is tuning the material's spectrum of absorption just right: It should absorb virtually all wavelengths of light that reach Earth's surface from the sun - but not much of the rest of the spectrum, since that would increase the energy that is reradiated by the material, and thus lost to the conversion process.

Improved Supercapacitors for Super Batteries, Electric Vehicles
Researchers at the University of California, Riverside have developed a novel nanometer scale ruthenium oxide anchored nanocarbon graphene foam architecture that improves the performance of supercapacitors, a development that could mean faster acceleration in electric vehicles and longer battery life in portable electronics.

Mapping the behavior of charges in correlated spin-orbit coupled materials
In a relatively recently discovered class of materials, known as spin-orbit Mott insulators, theorists have predicted the emergence of new properties at points just beyond the insulating state, when electronic manipulation can transform these compounds into conducting metals.

Supercomputers Join Search for 'Cheapium'
In the search for cheaper materials that mimic their purer, more expensive counterparts, researchers are abandoning hunches and intuition for theoretical models and pure computing power.

Iron-based process promises greener, cheaper and safer drug and perfume production
University of Toronto researchers have developed a series of techniques to create a variety of very active iron-based catalysts necessary to produce the alcohols and amines used in the drug and perfume industry.

Nanocrystal Catalyst Transforms Impure Hydrogen into Electricity
The quest to harness hydrogen as the clean-burning fuel of the future demands the perfect catalysts-nanoscale machines that enhance chemical reactions.
More Ruthenium Current Events and Ruthenium News Articles

Ruthenium: Synthesis, Physicochemical Properties and Applications

Ruthenium: Synthesis, Physicochemical Properties and Applications
by Gary P. Keeler (Editor)

Ruthenium in Catalysis (Topics in Organometallic Chemistry)

Ruthenium in Catalysis (Topics in Organometallic Chemistry)
by Pierre H. Dixneuf (Editor), Christian Bruneau (Editor)

The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry. As our understanding of organometallic structure, properties and mechanisms increases, new ways are opened for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as organic synthesis, medical research, biology and materials science. Thus the scope of coverage includes a broad range of topics in pure and applied organometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. The individual volumes of Topics in Organometallic Chemistry are thematic. Review articles are generally invited by the volume editors.

Ruthenium Compounds as Antineoplastic agents

Ruthenium Compounds as Antineoplastic agents
by Sreekanth Thota (Author), Rajeshwar Yerra (Author), S. S. Karki (Author)

Whilst the chemotherapeutic success of platinum is undeniable, it is by no means the perfect drug. It is not effective against many common types of cancer, drug resistance is common and it has a deplorable range of side effects, which can include nerve damage, hair loss and nausea. To overcome these limitations, some compounds based on ruthenium have been developed and tested against cancer cell lines. These compounds tend to cause fewer side effects compared to platinum drugs. Ruthenium compounds represent one of the great success stories of metals in medicine. Two ruthenium compounds are currently undergoing clinical evaluation as anticancer drugs NAMI-A and KP1019. A great deal of the remaining ruthenium complexes, these efforts are continue today with increased realization that new...

Ruthenium-Catalyzed Ionic Hydrogenation Reactions: Mechanistic Studies and Synthetic Applications

Ruthenium-Catalyzed Ionic Hydrogenation Reactions: Mechanistic Studies and Synthetic Applications
by Hairong Guan (Author)

Homogeneous hydrogenation of C=N bonds remains achallenge to catalysis, particularly when enantiofaceselectivity is needed. During the past decade someprogress has been made in this area; however, highenantioselectivities has been obtained only forlimited classes of imines or their derivatives. Thereis thus a great need to develop new catalyst systemsfor asymmetric hydrogenation of C=N bonds. This bookbegins with a brief literature survey on themechanisms of C=N hydrogenation, followed by adetailed description of ionic hydrogenation, analternative method and new concept for hydrogenation.The main focus of the book is on the scope andmechanism of ruthenium-catalyzed ionic hydrogenationreactions. This information should be useful toindustrial scientists who are seeking chemoselectiveand...

Ruthenium Complexes of Thioether Ligands: Syntheses, Structures and Spectral and Electrochemical Properties

Ruthenium Complexes of Thioether Ligands: Syntheses, Structures and Spectral and Electrochemical Properties
by Palaniandavar Mallayan (Author), Dr M. (Author)

Over the past four decades tris(diimine)Ru(II) complexes, particularly [Ru(bpy)3]2+, have attracted much attention as they can be used as potential solar energy converters and as effective sensitizers in the photolysis of water and the influence of diimine ligands have been examined. As many biological electron-transfer systems are based on copper and iron coordinated mainly to sulfur donor sites, we have investigated the effect of incorporating these donors on spectral and electrochemical properties of Ru(II) complexes and the results of our studies constitute the contents of this book. The book collects the synthetic methodologies and molecular structures of these complexes and discusses the nature of metal-ligand bonding in them. It includes the calculation of redox potentials of...

Ruthenium Catalysts and Fine Chemistry (Topics in Organometallic Chemistry)

Ruthenium Catalysts and Fine Chemistry (Topics in Organometallic Chemistry)
by Christian Bruneau (Editor), Pierre H. Dixneuf (Editor)

Molecular ruthenium catalysts, during the last decade, have provided new indispensable synthetic methods that cannot be promoted by other catalysts, and they now constitute an emerging field for the selective preparation of fine chemicals. The major reaction types for carbon-carbon and carbon-heteroatom bond formation, most of them with atom economy, are comprehensively discussed by leading experts. The authors highlight the most important discoveries in ruthenium catalysis and propose activation processes, some of them being still controversial. They illustrate the innovation and usefulness in organic synthesis of specific reactions including carbocyclization, cyclopropanation, olefin metathesis, carbonylation, oxidation, transformation of silicon containing substrates, and show novel...

Ruthenium Complexes as Anticancer agents

Ruthenium Complexes as Anticancer agents
by Sreekanth Thota (Author), S.S. Karki (Author), Rajeshwar Yerra (Author)

It could be noted from the literature that the presence of the Ru(II) complexes is found to have anticancer activities. Ruthenium metal is known for a long time. But its discovery as a therapeutic agent has recently. Researchers are focused on the synthesis of ruthenium complexes. Ruthenium has to be incorporated in a complex to make it soluble in body fluids.In the search for anticancer active metal complexes several ruthenium complexes have been reported to be promising as anticancer drugs.Ruthenium also has three main properties that make ruthenium complexes well suited metal for medicinal application. i) Ligand exchange rate, ii) The ability of ruthenium to mimic iron in binding to certain biological molecules. iii) The range of accessible oxidation states. Since...

Ruthenium based Fischer-Tropsch Synthesis: Effect of Crystallites and Clusters of Different Sizes From ?Nano? to ?Ãngstrøm?

Ruthenium based Fischer-Tropsch Synthesis: Effect of Crystallites and Clusters of Different Sizes From ?Nano? to ?Ångstrøm?
by Cathrin Welker-Nieuwoudt (Author)

The Fischer-Tropsch (FT) synthesis is the catalytic conversion of hydrogen and carbon monoxide into higher hydrocarbons. Although ruthenium is the most active catalyst in FT synthesis, the lower cost metals iron and cobalt are used commercially. Generally, increased catalyst performance is achieved with increased metal surface area and dispersion, though recent literature reports that cobalt, iron and rhodium crystallites below a certain size in the nanometer range display lower metal surface area specific activity and a high methane selectivity. There have also been several attempts to investigate the possibility to conduct a homogeneously catalysed FT synthesis, which can be considered as an extreme case of metal dispersion. The aim of this study is to investigate FT activity and...

  Ruthenium: An entry from Macmillan Reference USA's Chemistry: Foundations and Applications
by D. Paul Rillema (Author)

This digital document is an article from Chemistry: Foundations and Applications, brought to you by Gale®, a part of Cengage Learning, a world leader in e-research and educational publishing for libraries, schools and businesses. The length of the article is 294 words. The article is delivered in HTML format and is available in your Digital Locker immediately after purchase. You can view it with any web browser. “Chemistry: Foundations and Application” is an accessible four-volume set that covers chemistry’s laws, processes, applications and sub-disciplines, reviews the history of the field, including modern research and practical applications, and includes biographies of scientists past and present. Varied topics that examine and explain chemistry's many branches,...

Ruthenium(II) tris(2,2'-bipyridine) chelate as a chemiluminophore in extrinsic lyoluminescences of aluminium and magnesium in aqueous solution [An article from: Analytica Chimica Acta]

Ruthenium(II) tris(2,2'-bipyridine) chelate as a chemiluminophore in extrinsic lyoluminescences of aluminium and magnesium in aqueous solution [An article from: Analytica Chimica Acta]
by Q. Jiang (Author), M. Kotiranta (Author), K. Langel (Author), J. Suomi (Author), Hakan (Author)

This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Media Library immediately after purchase. You can view it with any web browser.

Ruthenium(II) tris(2,2'-bipyridine) chelate shows chemiluminescence (CL) both during dissolution of metallic aluminium in alkaline conditions, and during dissolution of magnesium metal in acidic conditions. The presence of peroxodisulfate ions strongly enhances the CL. Magnesium system provides considerably better detectability of the present chelate giving linear calibration plot spanning over many orders of magnitude of concentration down to subnanomolar concentration levels. The possible primary species...

© 2015