Yumi Ijiri

My current research focuses on synthesizing and understanding novel magnetic materials.

• One area of interest to me is in investigating the properties of very small magnetic particles, called “nanoparticles.”  I’ve been working with Sara Majetich and her students at Carnegie Mellon in order to understand what happens to magnets on such a small scale. I’ve been using an unusual method known as polarized small angle neutron scattering in order to get quantitative information about magnetic interactions.
• In addition, I have been exploring more recently, biomedical applications of magnetic nanoparticles and magnetic technologies, working with Maciej Zborowski and his group at the Cleveland Clinic, as well as Anna Samia and her students at Case Western Reserve.
• Another effect that I am particularly interested in, as a result of post-doctoral research I conducted at NIST, is a phenomenon known as "exchange-biasing." In this effect, the behavior of one magnetic material (ferromagnet) is biased as a result of exchange interactions with another (an antiferromagnet). The effect is of much current interest, for improving the capabilities of sensors in hard disk drives. Specifically, I have looked at a number of different systems such as Fe3O4/CoO, Co/CoO, Fe/FeF2, Fe3O4/NiO, NiFe/CoO, and the like.
• I have also collaborated with Art Smith and his students at Ohio University to investigate the behavior of magnetic gallium nitride films.  There is much interest in creating magnetic semiconductors as opposed to the usual magnetic metals or insulators.

This work has been supported by a number of grants and fellowships as listed below:

• NSF RUI (2016-present), principal investigator for “Magnetic morphologies and excitations in ferrite nanoparticle assemblies.”
• NSF RUI (2011-2015), principal investigator for “Determining magnetic structures in oxide-based nanoparticle systems.”
• NSF MRI (2009-present), co-principal investigator for “Acquisition of a powder x-ray diffractometer for research and undergraduate research training.”
• NSF-RUI (2007-2011), principal investigator for “Magnetic interactions in nanoparticle systems.”
• Research Corporation (2003-2008), principal investigator for “Magnetic finite size effects in iron-based nanoparticles.”
• ACS-PRF (2003-2007), principal investigator for “Exchange anisotropy in novel magnetic materials.”
• NASA (2004-2005), principal investigator for “Feasibility study of ferromagnetic/ferroelectric films for enhanced microwave applications.”
• NSF-CCLI (1999-2002), principal investigator for “A hands-on learning approach to understanding magnetic materials.” Sarah Stoll and John Scofield, co-principal investigators.  Through this grant, we have purchased and installed a vibrating sample magnetometer for use in intermediate and advanced lab classes and research here at Oberlin.
• ACS-PRF (1999-2002), principal investigator for “Magnetic exchange anisotropy with modified manganese intermetallics.”
• ACS-PRF (2001), summer faculty fellowship at Carnegie Mellon.
• NRC/NIST Postdoctoral research fellow (1996-1998).

I’ve also been involved in a number of other research projects, studying:

• the thermoelectric properties of rare earth intermetallics as part of my graduate research
• methods for improved ridge waveguide laser diodes at Polaroid
• the chemistry of silicon clusters at Bell Laboratories, now Lucent Technologies
• the behavior of phospholipid bilayers as an undergraduate thesis project
• the feasibility of ultrasonic nondestructive evaluation of buried metal interfaces while a summer intern at Westinghouse (now CBS so I won't bother with the hyperlink)