| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Nanomaterials | Monday Sessions |
| Session NM-MoM |
| Session: | Magnetic Properties |
| Presenter: | Andrei Slavin, Oakland University, USA |
| Authors: | A.N. Slavin, Oakland University, USA I.V. Lisenkov, Oakland University, USA V.S. Tyberkevych, Oakland University, USA |
| Correspondent: | Click to Email |
Artificial magnetic metamaterials formed by arrays of dipolarly coupled magnetic nanodots are promising candidates for applications in microwave signal processing. It has been shown recently, that an array of magnetic dots can be used as a reconfigurable magnonic metamaterial (RMM), since its metastable static state (and the corresponding microwave characteristics) can be switched by application of a pulse of a bias magnetic field [1-3].
In this work we present a theory of switching of a metastable static state in a magnetic metamaterial formed by an array of identical dipolarly coupled nanodots under the action of a short (duration of the order of 10-100 ns) magnetic field pulse. It is shown that a large array of magnetic dots cannot be switched into a perfect periodic antiferromagnetic state (AFM). Instead, the final state of an array after the end of the switching pulse comprises a set of clusters with the local AFM periodicity. The properties of the array’s final state strongly depend on the duration of the trailing front τf of the switching field pulse. In particular, the average size of the AFM clusters in the final state increases as A~ τf2/3. This increase in the regularity of a final state is limited by the thermally activated dot magnetization reversals that become possible if the switching field decreases too slowly. In particular, our results show that the distance of the signal propagation in a chain of magnetic dots may be increased by application of a clock pulse having a long trailing front. It is also demonstrated that using magnetic metamaterials it is possible to design of a magnonic phase shifter operating without an external bias magnetic field. The phase shifter uses a localized collective spin wave mode propagating along a domain wall “waveguide” in a dipolarly-coupled magnetic dot array with a chessboard antiferromagnetic (CAFM) ground state. It is also demonstrated numerically that the remagnetization of a single magnetic dot adjacent to the domain wall waveguide introduces a controllable phase shift in the propagating spin wave mode without significant change to the mode amplitude. Thus, it is possible to realize a logic XOR gate in the same system.
References:
1. J. Topp, et al., Phys. Rev. Lett. 104, 207205 (2010).
2. S. Tacchi, et al., Phys. Rev. B 82, 184408 (2010).
3. R. Verba, et al., Appl. Phys. Lett. 100, 192412 (2012).