Magnetic Nano-Width Domain in a Layered Ferromagnet
We have observed the evolution of magnetic domain structures in layered ferromagnets by means of low-temperature Lorentz transmission electron microscopy, and found a magnetic ripple state which signifies a formation of magnetic nano-domain. Magnetic domains in magnetic materials play an important role in device applications such as magnetic and magnetoresistive recording. In recent years there has been growing interest in microscopic investigation of magnetic domains due to the miniaturization of devices. In this paper, we investigated magnetic domain structures dynamically in nano-to-micro meter scale for single crystals of a layered ferromagnet, La2-2xSr1+2xMn2O7 (0.32 < x < 0.40), using Lorentz transmission electron microscopy. We have successfully observed various magnetic domain structures as well as a magnetic ripple state. Our high-resolution magnetic domain imaging revealed that the ripple state is characterized by evolution of plate-like magnetic gnanoh-width domains. The observed magnetic nano-domains provide a new possibility for memory devices with ultra high density.
Figure: Nano-width magnetic domains in La2-2xSr1+2xMn2O7 (x = 0.32) observed by Lorentz transmission electron microscopy. Both black and white regions indicate the magnetic domains. Arrows indicate the directions of magnetization at the respective domains.