8 Microwave-Driven Dynamics of Magnetic Skyrmions …
205
which indicates that these sets of microwave polarization and the spin-wave mode
are suitable for efficient conversion of microwaves to a DC electric voltage.
It should be also noted that an advantage of using a skyrmion crystal is that the
arrays of numerous magnetic skyrmions in a skyrmion crystal behaves as batteries
connected in series, which give a large electric voltage as a sum of each contribution.
We expect several orders of magnitude larger electric voltage by using a larger-sized
device, which offers a promising technique of an efficient conversion of microwaves
to DC electric voltages.
8.8 Concluding Remarks
To summarize this chapter, we have discussed several microwave-related phenomena
that magnetic skyrmions confined in a quasi-two-dimensional magnetic specimen
are expected to show under a tilted external magnetic field by particularly taking the
microwave-driven translational motion and the microwave-induced DC spin-motive
forces as topics. The researches on the dynamical phenomena and device functions of
magnetic skyrmions are now extended over a wide area. The researches on magnetic
skyrmions which bring technical applications into a scope can be classified roughly
into two categories. One category of the researches aims for application to magnetic
memories and storage devices and seek the elementary techniques to write, erase,
read, and drive magnetic skyrmions in controlled ways [3, 49]. Another category of
the researches focuses on the microwave-device functions of magnetic skyrmions
based on their peculiar spin-wave modes such as microwave generation, microwave
detection, microwave diode, and magnonic-crystal devices [4, 6, 7]. In addition,
magnetic skyrmions nowadays became to attract novel research interest as promising
building blocks of logic-gate devices [50] and brain-inspired computing devices such
as reservoir computing [51–53] and neuromorphic computing [54, 55]. It is yet to
be clarified what kinds of technical applications can be expected for the phenomena
discussed in this chapter. However, we naively anticipate that the magnetic skyrmions
under a tilted H ext field are still hiding a lot of intriguing phenomena, useful device
functions, and novel physics, which might be clarified in future studies.
References
1. S. Seki, M. Mochizuki, Skyrmions in Magnetic Materials (Springer, Berlin, 2015)
2. N. Nagaosa, Y. Tokura, Nat. Nanotechnol. 8, 899 (2013)
3. A. Fert et al., Nat. Nanotechnol. 8, 152 (2013)
4. G. Finocchio et al., J. Phys. D: Appl. Phys. 49, 423001 (2016)
5. K. Everschor-Sitte et al., J. Appl. Phys. 124, 240901 (2018)
6. M. Garst et al., J. Phys. D: Appl. Phys. 50, 293002 (2017)
7. M. Mochizuki, S. Seki, J. Phys.: Condens. Matter 27, 503001 (2015)
8. T.H.R. Skyrme, Proc. R. Soc. A 260, 127 (1961)
205
which indicates that these sets of microwave polarization and the spin-wave mode
are suitable for efficient conversion of microwaves to a DC electric voltage.
It should be also noted that an advantage of using a skyrmion crystal is that the
arrays of numerous magnetic skyrmions in a skyrmion crystal behaves as batteries
connected in series, which give a large electric voltage as a sum of each contribution.
We expect several orders of magnitude larger electric voltage by using a larger-sized
device, which offers a promising technique of an efficient conversion of microwaves
to DC electric voltages.
8.8 Concluding Remarks
To summarize this chapter, we have discussed several microwave-related phenomena
that magnetic skyrmions confined in a quasi-two-dimensional magnetic specimen
are expected to show under a tilted external magnetic field by particularly taking the
microwave-driven translational motion and the microwave-induced DC spin-motive
forces as topics. The researches on the dynamical phenomena and device functions of
magnetic skyrmions are now extended over a wide area. The researches on magnetic
skyrmions which bring technical applications into a scope can be classified roughly
into two categories. One category of the researches aims for application to magnetic
memories and storage devices and seek the elementary techniques to write, erase,
read, and drive magnetic skyrmions in controlled ways [3, 49]. Another category of
the researches focuses on the microwave-device functions of magnetic skyrmions
based on their peculiar spin-wave modes such as microwave generation, microwave
detection, microwave diode, and magnonic-crystal devices [4, 6, 7]. In addition,
magnetic skyrmions nowadays became to attract novel research interest as promising
building blocks of logic-gate devices [50] and brain-inspired computing devices such
as reservoir computing [51–53] and neuromorphic computing [54, 55]. It is yet to
be clarified what kinds of technical applications can be expected for the phenomena
discussed in this chapter. However, we naively anticipate that the magnetic skyrmions
under a tilted H ext field are still hiding a lot of intriguing phenomena, useful device
functions, and novel physics, which might be clarified in future studies.
References
1. S. Seki, M. Mochizuki, Skyrmions in Magnetic Materials (Springer, Berlin, 2015)
2. N. Nagaosa, Y. Tokura, Nat. Nanotechnol. 8, 899 (2013)
3. A. Fert et al., Nat. Nanotechnol. 8, 152 (2013)
4. G. Finocchio et al., J. Phys. D: Appl. Phys. 49, 423001 (2016)
5. K. Everschor-Sitte et al., J. Appl. Phys. 124, 240901 (2018)
6. M. Garst et al., J. Phys. D: Appl. Phys. 50, 293002 (2017)
7. M. Mochizuki, S. Seki, J. Phys.: Condens. Matter 27, 503001 (2015)
8. T.H.R. Skyrme, Proc. R. Soc. A 260, 127 (1961)