A team of researchers led by members of the ICN2 Photonic and Phononic Nanostructures group and the Physics and Engineering of Nanodevices group has designed a novel type of magnetic field sensor – i.e. a magnetometer – characterized by high-sensitivity and fast response.
Optomechanical cavities are devices able to amplify interactions between light and mechanical systems, which are used as very sensitive detectors of displacement. Thanks to the interaction of magnetic fields with mechanical elements, optomechanical devices can also serve to measure magnetic field, i.e. as magnetometers. In particular, the ability to measure small fields over a broad range of frequencies is relevant to many applications in geology, space exploration, biology and medical imaging.
Researchers from the ICN2 Photonic and Phononic Nanostructures group, led by ICREA Prof. Dr Clivia Sotomayor Torres, and the ICN2 Physics and Engineering of Nanodevices group, led by ICREA Prof. Dr Sergio Valenzuela, in collaborations with other institutions in Spain and Italy, have demonstrated the principle of a novel magnetometer, whose characteristics make it very competitive compared with other state-of-the-art magnetic field sensors. The results of this research – which has been supported through the ICN2 Severo Ochoa Programme – have been recently published in Physical Review Letters, in a paper signed by Martin Colombano Sosa as first author and by Dr Daniel Navarro-Urrios and Dr Marius V. Costache as corresponding authors.
This magnetometer consists of a hybrid resonator based on a thin film of a magnetic insulator, yttrium iron garnet, coupled to a glass microsphere optical cavity. It works on the principle of magnetostriction, which is a property of ferromagnetic materials that causes them to change their shape or dimensions under the effect of a magnetic field. This device shows significant magnetic field sensitivity (up to 850 pT Hz-1/2), dynamical range reaching 1 GHz and can be operated at room temperature. Thanks to these characteristics, as well as a rapid and broad frequency response, the magnetometer here presented can be used for fast imaging techniques. This hybrid device could also be applied in spintronics to study, for example, phonon-magnon coupling – where phonons are quantised vibrations of lattices and magnons are quantised spin waves.
Reference article
M. F. Colombano, G. Arregui, F. Bonell, N. E. Capuj, E. Chavez-Angel, A. Pitanti, S. O. Valenzuela, C. M. Sotomayor-Torres, D. Navarro-Urrios, and M. V. Costache, Ferromagnetic resonance assisted optomechanical magnetometer. Physical Review Letters 125, 147201 2020. DOI: 10.1103/PhysRevLett.125.147201