Spin@RT: Room Temperature Spintronics
Lead Research Organisation:
UNIVERSITY OF EXETER
Department Name: Physics
Abstract
The aim of spintronics is to control the electron spin so that it can be used to provide new functionality in a new generation of electronic devices. Within the pursuit of this aim there is a great deal of exciting cutting-edge fundamental physics and this is where our efforts will be concentrated. The first generation of spintronics has been with us for several years where devices such as read-heads for hard discs are a commonplace example of a metal-based device. There is also considerable research effort into the use of semiconductors in spintronics, but for reasons made clear in the case, we shall concentrate on metal and oxide spintronic research. Spintronics has reached a stage where further significant progress requires a new generation of devices based on a qualitatively different physics. Our proposal has four major themes. In the first we propose to exploit the new idea that the coherence of electron wave functions may be preserved during the transport of charge and spin across the entire thickness of an epitaxial magnetic nanostructure. It has been predicted that coherent transport will improve the magnetoresistance (MR) by more than an order of magnitude. The impact of such an improvement in MR alone on spintronic devices such as magnetic random access memory (MRAM) will be immense. In the second theme we intend to use the resolution of facility-based x-ray sources in an entirely new way, specifically, to observe the small but significant changes in the spin polarisation of a noble metal that result from injection of a spin-polarised current. This first direct measurement of spin accumulation will provide detailed information on spin-current torque which is currently missing but urgently required for the research described in the third theme. Such measurements will rely on our expertise in large area nano-device fabrication, the use of synchrotron radiation and high frequency measurements in micro-scale waveguides. In the third theme we will study the temporal and spatial coherence of the current-induced magnetic state of nano-pillar arrays using hitherto unexploited x-ray, neutron and time-resolved optical techniques to distinguish between analytical models for spin-transfer torque, and to understand the rich dynamic behaviour that has recently been reported. Close interplay between experiment and theory will allow us not only to understand but also to manipulate the dynamic behaviour through the choice of materials and experimental geometry. Finally, in the fourth theme, we will use nanofabrication to create novel nanao-wire structures from magnetoresistive materials and employ a powerful collection of magnetic characterisation tools to observe the current-induced motion of domain walls. This will allow us to resolve a number of critical but controversial issues such as the minimum current density required to induce wall motion, the intrinsic limit upon wall velocity, and the influence of domain wall structure.
Organisations
Publications
Abes M
(2009)
The spin polarization of Mn atoms in paramagnetic CuMn alloys induced by a Co layer
in Journal of Applied Physics
Abes M
(2010)
Spin polarization and exchange coupling of Cu and Mn atoms in paramagnetic CuMn diluted alloys induced by a Co layer
in Physical Review B
Keatley P
(2014)
Optical characterization of nonlocal spin transfer torque acting on a single nanomagnet
in Physical Review B
Keatley P
(2013)
Magnonics - From Fundamentals to Applications
Keatley P
(2008)
Time-resolved investigation of magnetization dynamics of arrays of nonellipsoidal nanomagnets with nonuniform ground states
in Physical Review B
Keatley P
(2015)
Resonant enhancement of damping within the free layer of a microscale magnetic tunnel valve
in Journal of Applied Physics
Keatley P
(2009)
Time- and vector-resolved magneto-optical Kerr effect measurements of large angle precessional reorientation in a 2×2µm2 ferromagnet
in Journal of Applied Physics
Keatley P
(2011)
Large amplitude magnetization dynamics and the suppression of edge modes in a single nanomagnet
in Applied Physics Letters
Keatley PS
(2011)
Ultrafast magnetization dynamics of spintronic nanostructures.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Kruglyak VV
(2010)
Imaging collective magnonic modes in 2D arrays of magnetic nanoelements.
in Physical review letters
Lepadatu S
(2010)
Domain-wall pinning, nonadiabatic spin-transfer torque, and spin-current polarization in permalloy wires doped with vanadium
in Physical Review B
Liu Y
(2010)
Optically induced magnetization dynamics and variation of damping parameter in epitaxial Co 2 MnSi Heusler alloy films
in Physical Review B
Telling N
(2008)
Evidence of local moment formation in Co-based Heusler alloys
in Physical Review B
Telling N
(2008)
Temperature dependence of the interface moments in Co2MnSi thin films
in Applied Physics Letters