News and events

21 March 2018

Magnonic studies of ferromagnetic nanostructures

Presented By Dr Guru Venkat (Loughborough University)

About this event


Nanomagnets find applications in sensors, transducers, oscillators and information storage. Collective excitations of the electron spin system in these materials are called spin waves (SWs) and are attractive candidates for information processing. The transfer and processing of data by spin wave quanta (or magnons) has led to the emerging research field of magnonics.

We first look at SW propagation in ferromagnetic waveguides, using micromagnetic simulations. We analysed the SW dispersion in these structures and propose a standard micromagnetic problem for use in the community. We also look at SW propagation in ferromagnetic nano-rings and defects in magnonic crystals and motivate functional SW devices from these studies. We formulate absorbing boundary conditions in micromagnetic simulations to mitigate SW reflections. A parabolic increase in Landau-Lifshitz damping at the boundaries causes lesser reflections than the commonly used abrupt increase in damping.

We then turn our attention to ferrite materials which are used for a variety of microwave and spin wave devices. We describe our magneto optic setup
to measure the hysteresis loop for a 7.6 micron thick (LuBi)3Fe5O12 (BLIG) film. We observe striped domain patterns using a transmission mode polarization microscope. We simulate these multiple stripe domains as well as the room temperature magnetization dynamics in this film. We carried out Brillouin light spectroscopy measurements for finding thermally driven magnon frequencies. We compare the simulation predictions and experimental results and draw conclusions.