A new ferrimagnetic-type magnetic metamaterial improves energy efficiency

So-called magnetic metamaterials are likely the future of small, reconfigurable microwave devices. Such devices have huge potential in developing future information processing technologies. Research published in the Journal of Applied Physics describes a new method to create a stable, reprogrammable ferrimagnetic-type magnetic state for these metamaterials.

The research created an artificial ferrimagnetic-type configuration for the metamaterial, where a population’s distribution of magnetic moments can produce a particular net magnetization. The authors used an array of tiny dipolar-coupled, rhomboid-shaped nanomagnets, which were made using lithography with two different widths, alternated in the array. On a micron scale, the array used ferrimagnetic-type ordering, giving nearest neighbor rhomboid nanomagnets opposite and unequal magnetic moments.

The rhomboid shape provides a unique magnetic configuration potential. Through various field initialization processes, an array of this shape can be preprogrammed with different magnetic configurations, making the array tunable. These processes involve applying an external magnetic field momentarily, in a particular sequence, to prepare the array’s magnetic states. In a device, this can be achieved by placing the material at a cross-point of DC current lines.

Metamaterials like this are important for technology continuing to shrink. Typically, arrays require tuning with external magnetic fields, which hinders device integration and low-power operation. This research presents a new solution for reconfigurable magnetization on a small scale without needing external bias fields. The new material is also more reliable than previous array designs based on dipolar-coupling, which often suffer from unavoidable structural defects and require careful and complex field initialization.

Source: “Reconfigurable magnetic and microwave properties of a ferrimagnetic-type artificial crystal,” by Arabinda Haldar and Adekunle Olusola Adeyeye, Journal of Applied Physics (2018). The article can be accessed at https://doi.org/10.1063/1.5032158 .