Context of project
Nowadays, our society has to deal with an enormous and ever increasing amount of data. Although, this data revolution has many positives to take for our lives, there are concerns regarding the sustainability of new technologies to fulfill the need of larger capabilities for data storage and rapid exchange of information.
We were invited to write a review/perspective article to cover this very topic, the efforts towards the development of energy-efficient storage devices. We recapitulated part of the main directions of the last years of research in condensed matter in storage mechanisms and energy harvesting.
Abstract of our review
The current data revolution has, in part, been enabled by decades of research into magnetism and spin phenomena. For example, milestones such as the observation of giant magnetoresistance, and the resulting development of the spin-valve read head, continue to motivate device research. However, the ever-growing need for higher data processing speeds and larger data storage capabilities has caused a significant increase in energy consumption and environmental concerns. Ongoing research and development in spintronics should therefore reduce energy consumption while increasing information processing capabilities. Here, we provide an overview of the current status of research and technology developments in data storage and spin-mediated energy harvesting in relation to energy-efficient technologies. We give our perspective on the advantages and outstanding issues for various data-storage concepts, and energy conversion mechanisms enabled by spin.
Spintronic devices for energy-efficient data storage and energy harvesting
J. Puebla, J. Kim, K. Kondou and Y. Otani
Communications Materials, 1, 24 (2020)
www.nature.com/articles/s43246-020-0022-5 (open access)
Context of project
Arguably, one of the most enlightening works by the late physicist Charles Kittel is the theoretical description of the ferromagnetic resonance absorption, published first in 1947  and extended to shape anistropies in 1948 . At these early works, Kittel described the magnetization dynamics exerted in a ferromagnetic specimen at resonance conditions. Nowadays, the FMR is a versatile tool that allows studying magnetization dynamics in thin films, spin waves, magnetization switching and spin pumping. Remarkably, 10 years after his description of FMR, it was the same Charles Kittel who first formulated the coupling of spin waves (magnons) and lattice vibrations (phonons) at resonance conditions, giving origin to the acoustic excited FMR .
Kittel's early works reference:
In the context of an invited contribution to the special issue on voltage control of nanomagnetism in the Journal of Physics D of the Institute of Physics (IOP), we published an overview of the current state of acoustic ferromagnetic resonance, a field we have been contributing in the last years. Our overview gives first a description of the mechanism of acoustic ferromagnetic resonance excited by surface acoustic waves, then we describe the generation of spin currents by a mechanism called acoustic spin pumping, and we also described briefly a relatively new related subject, the magneto-rotation coupling, a coupling of the rotation of the lattice with magnetic anisotropies. In memory of Prof. Charles Kittel who passed away the last May 2019 at the age of 102 years old.
Acoustic ferromagnetic resonance and spin pumping induced by surface acoustic waves
J. Puebla, M. Xu, B. Rana, K. Yamamoto, S. Maekawa and Y. Otani
Journal of Physics D: Applied Physics, Vol. 53, No. 26 (2020)