Fourier transform holography with extended reference by autocorrelation linear differential operator.  A lensless imaging technique to study magnetic domains with perpendicular and in-plane magnetization that promises a spatial resolution of ~15 nm.  In (g), a holographic image of a permalloy square element (500x500 nm, 50nm thick) with Landau domain pattern is observed.

Spintronics and Magnonics

This theme is led by Prof Rob Hicken, Dr Volodymyr Kruglyak and Dr Feodor Ogrin, working alongside Prof Bill Barnes, Prof Euan Hendry, Prof Roy Sambles and Prof Alastair Hibbins

Our research in spintronics and magnonics exploits our longstanding experience in the growth and characterisation of magnetic materials.  Basics properties such as magnetic switching are explored through magnetometry, while nanoscale probes ranging from magnetic force microscopy to soft x-ray holographic imaging are used to explore the internal magnetic structure of magnetic materials created in the laboratory.

We have particular expertise in the study of dynamic processes using microwave, optical and x-ray probes.   Fundamental ultrafast phenomena involving electron, phonon and spin dynamics are studied optically down to femtosecond timescales and with x-rays in the picosecond and nanosecond regimes.

The spin of the electron provides an additional degree of freedom with which to control the function of spintronic materials and devices.  While magnetoresistance effects have been exploited in magnetic sensors, most notably for reading data from a hard disk drive, the inverse effect, by which spin polarized electrons induce a spin transfer torque on a nanoscale magnet, is underpinning the operation of new active spintronic devices such as spin transfer oscillators, switches and amplifiers.

The intrinsic timescales for magnetization dynamics lie within the picosecond regime, where the fundamental magnetic excitation is the spin wave or magnon.  The field of nanoscale magnonics aims to control and exploit the excitation, propagation and detection of magnons, leading to new paradigms for microwave signal processing and low power logic chips.

New opportunities for magnetic materials constantly appear through the development of artificial multifunctional metamaterials.  Magnetic inclusions are being used to manipulate permeability and hence microwave refractive index within our Metamaterials and Transformation Optics theme, while plasmonics can either be used to sense magnetic materials in the near field, or exploit their bistable nature within device operation. Biomedical applications of magnetic materials include magnetic micro-motors and functional nanomagnets.

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