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Research published in the prestigious journal Applied Physics Letters 

World record in tunnelling magnetoresistance

25.05.2011 -

1904: the number for the world record in the measurement of tunnelling magnetoresistance (TMR) achieved in Trieste; a frontier of knowledge that could revolutionise computer memory performance or enable the creation of microsensors that are considerably more sensitive than, for example, those currently used in car ABS systems.


This is the science of spintronics, a combination of electronics and magnetism, whose development is closely linked to research on new materials, their configuration and the engineering process within the vast field of nanotechnology. A multidisciplinary field that requires considerably advanced techno-scientific expertise and state-of-the-art equipment, both of which are available at the Istituto Officina dei Materiali - CNR at AREA Science Park in Trieste.


Success was achieved as a result of the SPINOX project. Here researchers managed to manipulate, with the utmost precision and on an atomic level, a combination of titanium, manganese, strontium and lanthanum, creating a nanostructured configuration so close to theoretical models that they were able to produce magnetoresistance levels in the laboratory that had never before been attained.


Magnetoresistance is the property of a material to change the value of its electrical resistance when an external magnetic field is applied. The higher the magnetoresistance, the greater the possibility for creating more reliable and more energy-efficient microprocessors as well as new generations of magnetic field sensors for use in safety systems.


Bruce Davidson is the coordinator of SPINOX and a rare example of a researcher who moved from the United States to Italy, attracted by the quality of the scientific work being performed in Trieste. "In spintronics," explains Davidson, "we use, in addition to the electric charge of the electron, the magnetic field - or spin -  creating the conditions needed to produce miniaturised instruments with better performance and lower consumption.


Spintronics is a very recent approach but has already had an enormous technical and economic impact thanks to the use of giant magnetoresistance (GMR); this phenomenon was discovered by the Frenchman Albert Fert and the German Peter Grünberg and earned them the 2007 Nobel Prize in Physics. Up to a year ago, GMR was the basis for the operation of read heads in almost all modern computer hard disks. Now, however, a new generation of read heads is about to hit the market: they offer a better performance based on the quantum effects of TMR, resulting in an order of magnitude more sensitive than that of tiny magnetic fields."


The record achieved by the IOM-CNR led to the creation, by the group developing laboratory instrumentation, of an experimental apparatus that enables the synthesis of the nanostructure. This was made possible thanks to funding provided under regional law 26/2005 in Friuli Venezia Giulia.


"A significant advance in the development of new high-performance materials with submicroscopic or functionalised properties; these so-called smart materials," explains Roberto Gotter, Head of the Instrumentation Development Group at IOM-CNR, "are obtained through a synergy between innovative experimental devices, developed ad hoc and not mass-produced, and large research infrastructures.


For example, the Elettra synchrotron makes it possible to view, understand and control the synthesis process on an atomic scale in a way that is closely interrelated with the performance of magnetic tunnelling junctions. It is precisely through a strategic role such as this that, thanks to regional funding, IOM-CNR and the SPINOX project have been able to create a special experimental station for the synthesis of spintronics materials.


The station is in turn connected to the synchrotron beamlines, and by means of the high-performance X-rays generated by the Elettra storage ring, offers the international scientific community unparalleled synthesis and analysis capability".