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“It’s like taking two pieces of bread and putting them together and having the sandwich filling magically appear.”


By making calculations and modelling the basic physical properties of both materials, Randeria’s team has hit upon an explanation for the behaviour that seems ironic: the interface between two non-magnetic materials exhibits magnetism.


“Randeria’s team has hit upon an explanation for the behaviour that seems ironic: the interface between two non-magnetic materials exhibits magnetism.”


The team showed how the elemental units of magnetism, called “local moments,” are formed at the interface of the two materials. They then demonstrated how these moments interact with the conducting electrons to give rise to a magnetic state in which the moments are arranged in an unusual spiral pattern.


If the physicists’ explanation is correct, then perhaps someday, electronic devices could be constructed that exploit the interface between two oxides. Theoretically, such devices would combine the computational abilities of a silicon chip with the magnetic data storage abilities of permanent magnets like iron.


“If you had conduction and magnetism available in the same platform, it could be possible to integrate computer memory with data processing. Maybe different kinds of computation would be possible,” Randeria comments.


But those applications are a long way off. Right now, the physicists hope that their theoretical explanation for the strange magnetic behaviour will enable other researchers to perform experiments and confirm it.


This work is described in detail in the paper, “Ferromagnetic exchange, spin-orbit coupling and spiral magnetism at the LaAlO3/SrTiO3 interface,” by Sumilan Banerjee et al in Nature Physics (2013) published online on 25th August 2013. doi:10.1038/nphys2702


This research was sponsored by the U.S. Department of Energy, the National Science Foundation (NSF), and Ohio State’s Centre for Emergent Materials, one of a network of Materials Research Science and Engineering Centres funded by NSF.


Vishay launches AlGaAs 940nm IR emitter


The aluminium gallium arsenide device is suited to fast gesture remote control applications


Vishay Intertechnology is broadening its optoelectronics portfolio with the introduction of a new high-power, high-speed 940 nm infrared emitter for gesture remote control applications.


The AlGaAs VSLB9530S module offers a radiant power of 40 mW at 100 mA, and is offered in a clear molded, leaded TELUX package with an oval lens designed to support an angle of half


94 www.compoundsemiconductor.net August/September 2013 Custom MMIC releases 4 to


10GHz GaAs driver amplifier The gallium arsenide MMIC device is suited for communications systems requiring small size and high linearity. These include WiLAN, C and X Band communications systems,


intensity of +/- 18° in the vertical direction and +/- 36° in the horizontal direction.


The VSLB9530S is built on AIGaAs multi-quantum well (MQW) technology. The device’s angular distribution makes it ideal for gesture remote control of televisions and gaming systems, where it provides excellent spectral matching with silicon photodetectors.


The IR emitter’s wider angle in the horizontal view helps maintain position flexibility for users, while the narrower angle in the vertical plane focuses the distributed radiant intensity.


The TELUX package of the VSLB9530S measures 7.62 mm by 7.62 mm by 4.6 mm and provides a low thermal resistance of 200 K/W.


Vishay says while standard IR emitters typically offer drive currents to 100 mA, the low thermal resistivity of the VSLB9530S allows continuous drive currents up to 150 mA, which pushes the achievable radiant intensity to 60 mW/sr at 150 mA. The device offers high modulation bandwidth of 24 MHz and is suitable for high pulse current operation.


The infrared emitter offers fast switching speeds down to 15ns, low forward voltage down to 1.31 V at 150 mA, and an operating temperature range from -40°C to +95°C. Compatible with wave solder processes according to CECC 00802, the VSLB9530 is compliant to RoHS Directive 2011/65/EU, halogen-free per JEDEC JS709A, and conforms to Vishay’s “Green” standards.


Samples and production quantities of the new infrared emitters are available now, with lead times of six to eight weeks for large orders.


Vishay Intertechnology, Inc., manufactures discrete semiconductors (diodes, MOSFETs, and infrared optoelectronics) and passive electronic components (resistors, inductors, and capacitors).


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