Magnetic properties analysis in extreme environments

NPL's Ferromagnetic Resonance (FMR) measurement system is a powerful tool for studying the magnetic properties of materials and for developing new magnetic devices. The system can be used to measure the following magnetic properties of materials:

• Saturation magnetization
• Exchange coupling constant
• Anisotropy field

The system can also be used to study the following dynamics of magnetisation:

• Spin wave spectrum
• Damping of magnetisation precession

It would be of interest for people working in a wide variety of application areas, including:

• Magnetic sensors, such as read heads for hard drives and read heads for magnetic resonance imaging (MRI)
• Next generation magnetic memory devices, such as spin-transfer torque magnetic random-access memory (STT-MRAM)
• Microwave oscillators and amplifiers
• Terahertz sources

Ferromagnetic resonance (FMR) is a phenomenon that occurs when a ferromagnetic material is subjected to an oscillating magnetic field. The oscillating magnetic field causes the magnetisation of the material to precess, or rotate, at a specific frequency. This frequency is called the ferromagnetic resonance frequency.

Broadband FMR spectroscopy utilising the NanOsc CryoFMR-40 allows for dynamic property measurements up to 40 GHz. FMR over such a wide frequency range enables the extraction a variety of magnetic parameters, several which are traditionally inaccessible by static measurement techniques, as well as extracting parameters which can be correlated with those derived from static measurements.

From FMR NPL can:

• Calculate the effective magnetisation (Meff), anisotropy (K), gyromagnetic ratio (γ), damping (α), and inhomogeneous broadening (ΔHO)
• Enable the user to extract the exchange stiffness (A) and inverse spin Hall effect ISHE (e.g. spin Hall angle (θSHA)).

Our tests can be run in extreme environments at a temperature and magnetic field range of 5K-400K and 0T-9T respectively.

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