Researchers advance Fe4N as a spintronics conductor
Researchers advance Fe4N as a spintronics conductor lead image
Spintronics conduction, which utilizes the electrons’ spin in addition to charge, has great enhancement potential for complex devises that, for example, involve sensory, memory, and logic functions. However, developing a spintronics conductor that is inexpensive with a low damping constant is challenging.
Recently, a group of researchers from the University of Minnesota and the Naval Research Laboratory furthered the interest in Fe4N – which is inexpensive, producible at low temperatures, and displays auspicious qualities, such as low damping constant and high and negative spin polarization ratio – by fabricating thin Fe4N films on top of a Ta/Ru buffer and a Si substrate. Their Fe4N films measured well for spintronics conductivity and durability. They report on their research in AIP Advances.
The researchers deposited Fe4N on Ta/Ru and Si substrate stack with a modified facing-target-sputtering technique. They confirmed with point contact Andreev reflection (PCAR) technique that the Ta/Ru buffer, in comparison with other tested buffers, induced the thin Fe4N films to arrange in the (111) out-of-plane orientation sought for spintronics effectiveness. Lead author Xuan Li also highlights that their fine tuning the N ratio and temperature for Fe4N was also important for achieving the (111) out-of-plane orientation.
For the spin polarization ratio, the researchers tested with variations of PCAR fitted by a tailored Blonder-Tinkham-Klapwijk model. For 10, 20, and 40 nm Fe4N, they found similar spin polarizations 0.5, which the paper reports as device applicable.
Xuan says their investigation represents a material study-real world application hybrid. Coauthor Jian-Ping also points out this research offers an important transition for Fe4N research, with future crystalline texture experimentation yielding even higher spin polarization ratios.
Source: “Deposition and spin polarization study of Fe4N thin films with (111) orientation,” by Xuan Li, M. S. Osofsky, Kevin L. Jensen, Hongshi Li, and Jian-Ping Wang, AIP Advances (2017). The article can be accessed at https://doi.org/10.1063/1.4991963 .
