eNewsletter

June 2009

Multiferroics – Making a Switch the Electric Way
Berkeley Lab researchers have shown that electric fields can be used as ON/OFF switches in doped multiferroic films, a development that holds promise for future magnetic data storage and spintronic devices.

Multiferroics are materials in which unique combinations of electric and magnetic properties can simultaneously coexist. They are potential cornerstones in future magnetic data storage and spintronic devices provided a simple and fast way can be found to turn their electric and magnetic properties on and off. In a promising new development, researchers with the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) working with a prototypical multiferroic have successfully demonstrated just such a switch — electric fields.

Ramamoorthy Ramesh and Chan-Ho Yang of Berkeley Lab’s Materials Sciences Division successfully demonstrated that electric fields can be used as ON/OFF switches in doped multiferroic films, a development that holds promise for future magnetic data storage and spintronic devices.

“Using electric fields, we have been able to create, erase and invert p-n junctions in a calcium-doped bismuth ferrite film,” said Ramamoorthy Ramesh of Berkeley Lab’s Materials Sciences Division (MSD), who led this research.
“Through the combination of electronic conduction with the electric and magnetic properties already present in the multiferroic bismuth ferrite, our demonstration opens the door to merging magnetoelectrics and magnetoelectronics at room temperature.”

Ramesh, who is also a professor in the Department of Materials Science and Engineering and the Department of Physics at UC Berkeley, has published a paper on this research that is now available in the on-line edition of the journal Nature Materials. The paper is titled: “Electric modulation of conduction in multiferroic Ca-doped BiFeO3 films.” Co-authoring the paper with Ramesh were Chan-Ho Yang, Jan Seidel,Sang-Yong Kim, Pim Rossen, Pu Yu, Marcin Gajek, Ying-Hao Chu, Lane Martin, Micky Holcomb, Qing He, Petro Maksymovych, Nina Balke, Sergei Kalinin, Arthur Baddorf, Sourav Basu and Matthew Scullin.

The next generation of computers promises to be smaller, faster and far more versatile than today’s devices because of the anticipated development of memory chips that store data through electron spin and its associated magnetic moment rather than electron charge. Because multiferroics simultaneously exhibit two or more ferro electric or magnetic properties in response to changes in their environment, they’re considered prime candidates to be the materials of choice for this technology.

Bismuth ferrite is a multiferroic comprised of bismuth, iron and oxygen (BiFeO3). It is both ferroelectric and antiferromagnetic (”ferro” refers to magnetism in iron but the term has grown to include materials and properties that have nothing to do with iron), and has commanded particular interest in the spintronics field, especially after a surprising discovery by Ramesh and his group earlier this year. They found that although bismuth ferrite is an insulating material, running through its crystals are ultrathin (two-dimensional) sheets called “domain walls” that conduct electricity at room temperature. This discovery suggested that with the right doping, the conducting states in bismuth ferrite could be stabilized, opening the possibility of creating p-n junctions, a crucial key to solid state electronics.

This image recorded after an electric field was applied to a calcium-doped bismuth ferrite multiferroic film shows in the top image current being conducted within the red rectangle (On). In the bottom image, an opposite electric field was applied to the area within the green rectangle, switching it back to an insulating state (Off).

“Insulator to conductor transitions are typically controlled through the combination of chemical doping and magnetic fields but magnetic fields are too expensive and energy-consuming to be practical in commercial devices,” said Ramesh. “Electric fields are much more useful control parameters because you can easily apply a voltage across a sample and modulate it as needed to induce insulator-conductor transitions.”

In their new study, Ramesh and his group first doped the bismuth ferrite with calcium acceptor ions, which are known to increase the amount of electric current that materials like bismuth ferrite can carry. The addition of the calcium ions created positively-charged oxygen vacancies. When an electric field was applied to the calcium-doped bismuth ferrite films, the oxygen vacancies became mobile. The electric field “swept” the oxygen vacancies towards the film’s top surface, creating an n-type semiconductor in that portion of the film, while the immobile calcium ions  created a p-type semiconductor in the bottom portion. Reversing the direction of the electric field inverted the n-type and p-type semiconductor regions, and a moderate field erased them.

“It is the same principle as in a CMOS device where the application of a voltage serves as an on/off switch that controls electron transport properties and changes electrical resistance from high (insulator) to low (conductor),” said Ramesh.

Whereas a typical CMOS device features an on/off switching ratio (the difference between resistance and non-resistance to electrical current) of about one million, Ramesh and his group achieved an on/off switching ratio of about a thousand in their calcium-doped bismuth ferrite films. While this ratio is sufficient for device operation and double the best ratio achieved with magnetic fields, Chan-Ho Yang, lead author on this Nature Materials paper and a post-doc in Ramesh’s group says it can be improved.

“To make the ON state more conductive, we have many ideas to try such as different calcium-doping ratios, different strain states, different growth conditions, and eventually different compounds using the same idea,” Yang said.

A year ago, Ramesh and his group demonstrated that an electric field could be used to control ferromagnetism in a non-doped bismuth ferrite film. (See Nature Materials, “Electric-field control of local ferromagnetism using a magnetoelectric multiferroic”)
With this new demonstration that the combination of doping and an applied electric field can change the insulating-conducting state of a multiferroic, he and his colleagues have shown one way forward in adapting multiferroics to such phenomena as colossal magnetoresistance, high temperature superconductivity and SQUID-type magnetic field detectors as well as spintronics.

This schematic diagram shows a calcium-doped bismuth ferrite multiferroic film existing in a highly insulating state until the application of an electric field mobilizes oxygen vacancies to create n- and p-type conductors in the top and bottom portions of the film respectively.

Said Yang, “Oxides such as bismuth ferrite are abundant and display many exotic properties including high-temperature superconductivity and colossal magnetoresistance, but they have not been used much in real applications because it has been so difficult to control defects, especially, oxygen vacancies. Our observations suggest a general technique to make oxygen vacancy defects controllable.”

Much of the work in this latest study by Ramesh and his group was carried out at Berkeley Lab’s Advanced Light Source (ALS), on the PEEM2 microscope. PEEM, which stands for PhotoEmission Electron Microscopy, is an ideal technique for studying ferro magnetic and antimagnetic domains, and PEEM2, powered by a bend magnet at ALS  beamline 7.3.1.1, is one of the world’s best instruments, able to resolve features only a few nanometers thick.
“Without the capabilities of PEEM2 our experiments would have been dead in the water,” said Ramesh. “Andreas Scholl (who manages PEEM2) and his ALS team were an enormous help.”

This research was primarily supported by the US Department of Energy’s Office of Science through its Basic Energy Sciences program.

Berkeley Lab is a US Department of Energy national laboratory located in Berkeley, California.  It conducts unclassified scientific research and is managed by the University of California.

Allegro MicroSystems Introduces a Three-Wire, Dynamic, Peak-Detecting, Differential Hall-Effect Sensor
Simplify your Design with the Ability to Sense Numerous Targets
Allegro MicroSystems, Inc. has introduced a differential analog Hall-effect sensor that switches in response to changing magnetic fields. This device has enhanced EMC capability that will allow users to optimize their finished sensor module by reducing their external component count, and in some cases, removing the PCB module. The combination of reduced component count, EMC enhancements, a dynamic self-calibrating algorithm and the flexibility to sense numerous types of targets simplifies the design-in process for a wide variety of applications.

The ATS617LSG is a differential analog Hall-effect sensor that switches in response to changing magnetic fields. The device uses an analog peak-detecting algorithm, automatic gain control and an integrated tracking capacitor to provide accurate edge detection corresponding to a rotating ferrous target. The peak-detecting algorithm is ideal for use in camshaft applications with the ability to sense a wide range of target geometries including fine pitch, encoded targets.

Allegro’s ATS617LSG is offered in the “SG” magnetically integrated package. The SG is a single step over-molded package, which consists of a samarium cobalt magnet and a Hall-Effect IC, further simplifying the design-in process. It is lead (Pb) free, with 100 percent matte tin lead frame plating.  It is priced at $2.55 in quantities of 1,000 and has a 14 to 16 week lead-time to market.

BI Technologies’ Ferrite Cube Inductor Deployed in Computer Power Applications
Providing design engineers with a robust, cost-effective through-hole device that requires minimal board space, TT electronics BI Technologies has extended its family of high-current, low-loss power inductors.  The HM58 series inductor features a heavy-gauge coil wire and exhibits a saturation current rating up to 60 A at frequencies to 1 MHz, making it well suited for motherboard and computer power applications.

“We’ve seen an increased demand for an inductor that delivers high-performance operating specifications but requires minimal PC board space,” said Donna Schaefer, application engineering manager for BI Technologies.  “With its through-hole configuration and three open sides, the inductor requires a footprint of 11 mm by 11.5 mm. As such, we are seeing the inductor used in a number of voltage regulator applications where board space is constrained.”

The RoHS-compliant HM58 series high current cube inductor features inductance values from 0.36 mH to 1.30 mH, depending on device. DCR ratings are from 0.65 mΩ to 1.05 mΩ, with tolerances to ±5 percent.  Operating temperature range is from -40°C to 125°C. The inductor is available in standard tray packaging. BI Technologies will also produce devices outside these specifications to meet customer requirements.

Typical pricing for the HM58 series inductor is approximately $0.39 each in quantities of 10,000 pieces.

austriamicrosystems Introduces 14-Bit Magnetic Rotary Encoder IC with Best-in-Class Device Protection for Tough Automotive Applications
austriamicrosystems, a global designer and manufacturer of high performance analog ICs for automotive, communication, industry and medical applications, has introduced AS5163, the first magnetic rotary encoder IC specifically designed to satisfy stringent automotive requirements in angle sensing applications where robust IC protection is essential.

austriamicrosystems’ newest automotive magnetic encoder IC incorporates both 27 volt overvoltage protection and -18 volt reverse polarity at supply pins. AS5163 also features an intelligent short circuit monitoring function to protect it against damage under short circuit condition. This makes the encoder IC well suited for automotive applications, such as throttle or gas-pedal systems.

“In the automotive industry with its constantly growing demands with regard to device protection and system reliability, our AS5163 is perfectly positioned to meet these challenges,” said Andreas Pfingstl, product manager, Automotive Encoders at austriamicrosystems. “When developing this device, we put special emphasis on the ease of use and cost efficiency for the user. The AS5163 offers a single-wire interface and, together with its robust protection features, allows system designers to meet their performance and reliability requirements, while optimizing system cost.”

The AS5163 single wire pin can be configured either as a 14-bit digital, 12-bit PWM or ratiometric analog output. In addition, the IC can be customized by the user to cover any system specific angle range. The programming of the desired angle range is achieved by simply setting a start and end position of the rotational movement. This feature makes AS5163 extremely flexible and easy to use in a variety of automotive angle sensing applications.

The AS5163 is operational over an ambient temperature range from -40°C to 150°C. It is available in a small TSSOP 14 package and operates at 5 V supply voltage.

Standex Electronics Unveils 3.7 mm Magnetic Reed Switch
Standex Electronics has introduced a magnetic reed switch – measuring 3.7 mm in length.  In addition to being able to fit in very small spaces, the GR150 also maintains a very narrow sensitivity range. With a magnetic sensitivity of 2 to 4 Ampere Turns (AT), typical operating time of 0.2 milliseconds (typical) and a release time of 0.1 milliseconds (typical) this professional grade ultra miniature reed switch is well suited for very demanding applications such as within hearing aids, in pill cams, flip or slide phones, laptop computers and more. 

Designed for applications where the available magnetic field is extremely low and/or the space limitations are a major design factor, the GR150 functions as a non-contact position sensor.  It features PGM alloy contacts and has a power rating of 1 VA maximum.  A switching current (Max) of 0.05 amp, DC is standard, as is a carry current rating (max) of 0.5 amp, DC.  Boasting an operating range of -40°C to 125°C, the GR200 is well suited for use wherever small size and sensitivity are required for non-contact position sensing applications.   

“With its ultra-miniature size and extreme sensitivity, the GR150 addresses the needs of design engineers in many industries” said Standex VP Tom Gould.  “In addition to proving a non-contact position sensor in a very small space, the GR150 also offers performance – with a range of 2 to 4 Ampere Turns available.”  

Designed primarily to address the needs of medical device manufacturers for use within hearing aids, pill cams and other surgical and medical devices, the GR150 is also applicable for other markets such as consumer electronics, industrial applications, military and aerospace, and more. 

High Sensitivity Coil for Hearing Aid Applications
Premo enlarges its telecoil family with the TC0502 series, a high reliability and sensitivity coil for application in hearing aids developed according to the highest quality standards (ISO/TS16949:02,ISO9001:2000).

The telecoil is wound with thin copper wires up to 0.012 mm diameter and inductance values between 40 and 270 mH. The TC0502, achieves a high sensitivity to magnetic field in 1 kHz (operation frequency in this kind of devices). The ferrite core material provide a stable performance in a wide range of temperature (-10ºC to 40ºC).

The Surface Mounting Device (SMD) configuration allows an easy integration in an automated printed circuit board assembly process, avoiding handling of the piece that could damage winding wire of the piece. This makes the piece different regarding main existing telecoils, commonly with a "thru-hole" configuration (that requires an additional wave soldering process).

These components, included in most of existing hearing aid devices, work as magnetic field sensor, turning the magnetic field into electric voltage as a standard microphone does with the acoustic energy. This allows the hearing handicapped people to receive the signal from a magnetic inductive loop located in public buildings and transports. Additionally these components improve binaural communication (stereo sounds) and phone, television and radio hearing.

Besides, the inclusion of this kind of coil in compatible hearing aid with mobile phones, the user can change the phone coil in manual or automatic way, to create a magnetic field as intensive as to transmit the signal to hearing aid.

The quality and reliability of this telecoil has been evaluated positively for the main hearing aid manufacturers. The TC0502 family is offered with electrics characters “custom” according to customers need.

New Permanent Magnet DC Gearmotors Offer Full-Featured Integral Speed Control Option
Bison Gear & Engineering has introduced six standard models of new parallel shaft permanent magnet DC gearmotors with continuous torque ratings from 30 to 500 in-lbs. (3.4 to 56.5 N-m). The new VWDIR134 DC gearmotors are available with 1/10 or 1/11 horsepower (74.6 or 67.8 watts) 90 volt brushed DC electric motors. The compact, integral gear reducers feature hardened steel helical and spur gearing for efficiency and durability, with ratios ranging from 10:1 to 266:1 and corresponding fixed output speeds from 152 to 6 RPM. The gearmotors feature built-in face mounting, compatible with Von Weise Genesis mounts, and offer overhung load (OHL) capability of 300 lbs. (136.4 kg.).  For added versatility, these gearmotors also accept the new Bison TightDrive speed control.

"The TightDrive option enables machine builders to put the control, the power and the gearmotor more conveniently at the point of use, while saving installation time and reducing costs," said Gary Dorough, Bison Gear western regional sales manager. "As a bonus, users can maximize energy savings by easily changing speeds as their requirements change."

Bison Gear's TightDrive motor-mounted speed control can be installed by the user on the rear of the VWDIR134 gearmotors and offers up to a 20:1 speed range. The TightDrive is housed in a durable aluminum extrusion, which offers NEMA 1 (IP 30) protection and superior heat dissipation. Speed is controlled with a combination on/off switch and speed potentiometer. In addition, three easily accessible adjustable potentiometers provide settings for minimum RPM, maximum RPM, and current limiting. The simple, yet innovative, SCR control architecture also provides much tighter speed regulation than alternative controls.

The TightDrive is designed for 115 volt 50/60 Hz operation and comes complete with three foot (0.9m) power cord and NEMA 5-15P plug. Users can mount the drive directly to the motor in 90° increments to optimize position of cord exit and motor leads.

The new VWDIR134 DC parallel shaft gearmotors are designed for high torque commercial, industrial and agricultural applications such as in foodservice, office and medical equipment as well as a wide variety of conveying equipment.

nanoTherics Launches magneTherm - a Hyperthermia Device with Frequency Selection
nanoTherics, a scientific medical research devices company founded in 2007, is has launched magneTherm, a new device designed to measure thermal effects of magnetic nanoparticles for hyperthermia applications.  The system is unique and is the only commercially available hyperthermia device available for measuring these thermal effects that includes flexibility in frequency selection.

nanoTherics’s primary business is supply of improved scientific devices and associated products to research laboratories in the pharmaceutical and biotechnology industries as well as academia. The company’s main products follow from more than 30 years combined cutting edge research into magnetic nanoparticle use conducted at Keele University and University of Florida and apply a patent-pending technology using nanoparticles and magnetic fields to facilitate enhanced delivery of biomolecules, such as DNA, into living cells.

“We are delighted to launch the magneTherm,” said Dr Linda Cammish, CEO. “It follows our March 2009 launch of the magneFect-nano, which uses proprietary oscillating magnetic arrays to promote particle/DNA uptake into cells to improve gene transfection whilst maintaining cell viability The introduction of these systems is illustrative of our expertise in magnetic nanoparticle technology for a range of life science research and human health applications, in the emerging field of nanomedicine arena and shows our commitment to product development to meet customer’s needs.”

Magnetics 2010 - Call for Presentations Deadline is July 31st
Magnetics 2010, taking place January 28-29, 2010 in Orlando, Fla., will focus on the latest advancements in magnetic applications, technology and materials. Serving OEM developers of products that utilize magnets and magnet systems, design engineers, OEM developers involved in EMC technology and magnetic effects, magnetics manufacturers and integrators, and material suppliers in the magnetics industry.

Be Part of the World's Premier Forum on Magnetic Applications, Technology and Materials
The Magnetics 2010 conference committee is currently accepting presentation abstracts.

There are a limited number of speaking slots, submit an abstract early as abstracts will be considered on first-come basis.
Deadline to submit an abstract is July 31st.

Submissions are sought for, but not limited to:

For questions regarding the program, or to send in an abstract contact Heather Krier.

Interested in hosting a workshop?
Contact Heather Krier for more information.

Sponsorships & Exhibits
In 2010, the Magnetics Conference will be co-located with the Motor, Drive & Automation Systems Conference. We feel this addition to be a natural fit, one that will provide added benefit to attendees, exhibitors and sponsors of both these world class technical events.
Contact Sue Hannebrink for more information.

Did you Miss the 2009 Magnetics Conference?
The conference proceedings from the 2009 Magnetics Conference held in Chicago, Ill. on April 15-16, are available on CD-ROM and include audio and video of select presentations.

Click Here to Order!

Murata Power Solutions Appoints North America Distribution Manager
Murata Power Solutions has appointed John Barnes as distribution manager for North America. John comes to Murata Power Solutions after 30 years at what now is Lineage Power Systems. John brings a wealth of experience to the job from his years with what was then AT&T Microelectronics, then Tyco Power and most recently Lineage Power.

Beyond his experience in distribution, John has also managed rep territories, held sales management responsibilities for global accounts and led design engineering teams. This breadth of experience will bring value to Murata Power Solutions’ channel partners and customers. In his new role John will be responsible for the overall management of all North America distribution activities that form a vital part of the company’s overall strategic plan. His responsibilities encompass Murata Power Solutions’ complete product range that includes DC/DC converters, AC/DC power supplies, magnetics, data acquisition devices and panel meters.

“I am delighted to welcome John to our team,” said Bret Murphy, director of Global Distribution at Murata Power Solutions. “His experience will prove invaluable in helping him meet the needs of our customers, and I am sure that his skills will enable us to further strengthen our position in the power sector across North America.”

Where Are All Those Needed Rare Earths Coming From?
By Ian London, Vice President Corporate Development, Avalon Ventures Ltd.

When I was first introduced to the magnet industry several years ago, the buzz was, and continues to be today, about the growing number and volume of applications, especially in rare earth magnets. It was exciting to learn how rare earth magnets were making energy efficient car designs, quieter and ‘maintenance-free’ wind turbines, mobile MRI machines, and other environmentally friendly technologies possible.

To read full article click here.

Download a PDF Copy of the Summer 2009 Issue of Magnetics Business & Technology Magazine

ISSUE INCLUDES:

• Research & Development
• Feature Articles / Columns
• New Magnetics Products / Technology
• Industry News

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