Electronic devices which store information through magnetisation rely on magnetic switching, typically enabled by localised magnetic ﬁelds (generated via electromagnetic induction) or by spin-polarised electric currents (spin-transfer torque). However, both systems require relatively high electric currents which heat up materials, resulting in significant energy loss through heat dissipation - the so-called Joule effect.
Energy efficiency could be increased if the necessary magnetic fields and electric currents could be reduced. This is achievable by lowering the coersivity (the ability to withstand an external magnetic field without becoming demagnetised) of the actuated material. Recent advances in this area have only reported significant success below 300 Kelvin and only with ultra-thin films or nanoparticles. However, the EU-funded SPIN-PORICS project recently announced the successful creation of a new material with sponge-like properties, with promise to advances efforts.
A new nanocomposite prototype
The SPIN-PORICS (Merging Nanoporous Materials with Energy-Efficient Spintronics) project team reported in the journal Advanced Functional Materials
that they had created the first prototypes of nanoporous magnetic memories, based on copper and nickel alloys (CuNi). The interior of these CuNi films were organised like a sponge, with only 5 or 10 nanometres spaces between pores, limiting space in the pore walls to a few dozen atoms. This nanoporous layer was filled with a dielectric material, where the magnetic properties were tuned at room temperature (RT) by using liquid electrolytes to apply voltage.
The project team reported being able to achieve a 35% reduction of magnetic coercivity, meeting the energy consumption required to reorientate the magnetic domains which is necessary for data recording. This result is due to the nanoporous design which enables the whole film - not only the surface - to participate in the electromagnetic effect.
Summarising the success of the prototype project coordinator Professor Jordi Sort has said, ‘The nanopores found on the inside of nanoporous materials offer a great amount of surface. With this vast surface concentrated in a very small space we can apply the voltage of a battery and enormously reduce the energy needed to orientate the magnetic domains and record data. This represents a new paradigm in the energy saving of computers and in computing and handling magnetic data in general.’
Introducing a new paradigm for spintronics
The digital revolution relies on increases in hard disk capacity and data processing speed and both have benefited from advances in magnetism and spintronics (spin transports electronics – which exploits electron spin and magnetisation). More broadly, developments in information and communication technology depend on overcoming the energy inefficiencies lingering in magnetoelectronic devices. It is estimated for example that with computers, 40% of energy is lost through heat dissipation. This means that companies such as Google chose to locate their computer servers underwater or in Nordic countries to assure low temperatures.
The SPIN-PORICS team foresees the new nanocomposite material principally benefiting three technological applications: electrically-assisted magnetic recording, voltage-driven switching of magnetic random-access memories and spin field-effect transistors. Given that some calculations suggest that substituting electric current for voltage in data processing systems could reduce energy costs by a factor of 1/500, this new paradigm could have a significant economic impact. According to Professor Jordi Sort, ‘Implementing this material into the memories of computers and mobile devices can offer many advantages, mainly in direct energy saving for computers and considerable increase in the autonomy of mobile devices.’
For more information, please see:CORDIS project webpage