ELEctric Control of nanoscale MAgnetic DEvices – ELECMADE

The International Technology Roadmap for Semiconductors (ITRS) has forecasted that the semiconductor industry will hit a ‘red brick wall’ by 2016, after which no known technologies exist to enable continued advances in device performance and storage capacities. It is clear that breakthroughs are needed and nanomagnetic systems provide unique opportunities. Particularly, spin-based memory and logic devices could complement or supplant traditional semiconductor microelectronics. Present spintronic devices are complex metal hetero-structures, for which their basic functionality arises from spin dependent scattering of polarized currents by magnetic layers separated by a non-magnetic spacer layer. In current spintronic devices (TMR read heads, MRAM sensors, etc) the orientations of the magnetic elements within devices are controlled by external magnetic fields. However it is now well established that the relative orientations of nano-magnets can be controlled directly by the injection of spin polarized currents which applies a torque on the magnetization. Device applications include spin-torque MRAM, high frequency non-linear oscillators, three dimensional solid state memories, and potentially magnetic logic operations. Spin-torque MRAM is projected to achieve low programming energies compared to FLASH memory cells. However, like other disruptive embedded memory technologies, it faces many challenges and even possible drawbacks.
New successful beyond CMOS approaches have to be able to provide ultralow power consumption for portable memory systems in particular. A novel solution can emerge from electric field (E) control of spintronics devices. In a recent study, two partners of ELECMADE provided the first experimental demonstration that the magnetic coercivity of ultra-thin metal films (FePt and FePd) can be controlled by electric charging (Science 315, 349 (2007)). This result opens the prospect of electric field (E) activation in metals emerging as an alternative to magnetic field or electric current activation to control the properties of magnetic nanosystems, with potential substantial gains in terms of device architectures and power consumption. However this requires that E-activation in metals be better understood, thanks to detailed experimental studies and associated theoretical analyses.
In the ELECMADE project, we propose to study the relatively unexplored and emerging field of using electric fields to control the intrinsic magnetic properties (e.g. Curie temperature, Antiferromagnetic-ferromagnetic transition, magnetic anisotropy and exchange bias field) in metallic systems and integrate these effects into novel 3 terminals solid state spin-based devices. The research project will address the control of the intrinsic magnetic properties of transition metals and their alloys and compounds. All studied systems will be chosen such that they magnetically order near or above room temperature. Because these materials are conducting, the E-field (and its effect on magnetism) manifests itself via charging effects, which are confined to the near surface region; therefore this research will focus on thin films and heterostructured devices where the surfaces can dramatically affect the magnetic properties. The 2 main goals will be to:
(i) Systematically investigate the E-field effects on the magnetic properties (anisotropy, ordering temperature, exchange bias) of transition-metal films and the coupling at magnetic-oxide/metal interfaces.
(ii) Use E-field control of magnetism and spintronic phenomena in integrated 3 terminal devices.
The research will explore new phenomena in E-field control of nanomagnetic systems with the transformative goal to provide the scientific underpinnings of next generation energy efficient, ultrafast and ultrasmall magneto-electronic devices.