Spin waves in ferromagnetic metallic wires

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Micro- and nanowires are like small antennas. In presences of an electromagnetic field, like radio waves, they develop a longitudinal electrical current that can be detected by an electronic circuit. If this small metallic antenna is also magnetic, the induced electrical current in the wire can be strongly modified by an external magnetic field. This effect, called magnetoimpedance, can be used to detect very small magnetic field. This is useful for applications such as geo-prospection, detection of metallic objects or biomedical imaging. We can also build an artificial material, made out of a thin layer of small magnetic nanowires, like a forest of small cylindrical magnets. This so-called magnonic crystal is sensitive to the radio waves used in wireless technologies. Therefore, the magnonic crystal can be useful in applications, such as cell phones, to detect and process wireless signals. The research proposed in this Discovery Grant aims to develop a fundamental understanding of how these magnetic micro- and nanowires respond to electromagnetic fields. What makes these magnetic wires special is that the microscopic magnets, called spins, responsible for their magnetic properties can be excited like small waves, at specific frequencies. These spin waves interact with the electromagnetic signal to be detected and with the electrical currents in the wires. We investigate how this interaction can be exploited to detect, transport or transform signals in ways that are not possible in simple metals. The funds requested are essentially for the financial support of the research of two PhD students and five undergraduate students for summer research projects. Possible outcomes of the work include new microwave materials or new design possibilities for wireless technologies and better magnetic sensors.