Principal Investigator :

Nicolas Bizière ()
CEMES (NMAT/NMATMAG)

Type of project : Disruptive Project

Date (start/end) : 2015 - 2017

Abstract

Magnonic crystals are the magnetic counterpart of photonic crystals. They are made of a magnetic material with a spatial modulation of one or several magnetic parameters. They are used for propagation of information in the Giga Hertz range coded as electromagnetic waves called spin waves. Due to the modulation of the magnetic parameters, forbidden frequencies, called band-gaps, rise for propagating spin waves. One of the major interests of these systems is that the band gaps can be tuned by an external magnetic field.

As spin waves wavelengths are orders of magnitude smaller than electromagnetic waves at the same frequencies, magnonics crystals can be considered as a reliable alternative to reduce the dimensions of RF sensors such as inductive antennas, whose sensitivity depends intrinsically on their size.

The HEUMAC project has two major objectives. The first one consists in making magnonic crystal with He ⁺ ion irradiated Co ₂ MnSi alloys. One ambitious point is to demonstrate that magnonic bandgaps can be created by a periodic modulation of the dynamic losses. Indeed, this parameter is generally neglected in the different models developed up to now. However, microwave losses act as a modulation of the local impedance of the waveguide and should have an impact on the propagation properties. The interest for using Heusler alloy in this project relies on the fact that depending on the crystallographic phase, the extrinsic or intrinsic losses can be modulated by ion irradiation. The second objective of the project aims at detecting the propagating spin wave at the output of the crystal by an electrical measurement. More specifically, the possibility to realize an in-situ demodulation of the signal via the magneto-resistance of the material allows simplifying the receiver demodulation stage of the device. From a fundamental point of view this experiment will rule on the effect of dynamic losses in the formation of frequency band-gaps. From a technological point of view, our detection method can pave the way to decrease energy consumption of microwave devices..