Photo of Yumi Ijiri
  • Professor of Physics
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Education

  • BA, Princeton University, 1991
  • MS, Cornell University, 1994
  • PhD, Cornell University, 1996

Recent Courses

Below is a list of courses that I’ve taught while here at Oberlin:

  • FYSP 143: Deconstructing Technology
  • CHEM65/PHYS 65: Deconstructing the Computer: the Nature of Electronic Materials. Co-taught with Sarah Stoll, formerly in the chemistry department.
  • PHYS 104: Elementary Physics II
  • PHYS 110: Mechanics and Relativity
  • PHYS 111: Electricity, Magnetism, and Thermodynamics
  • PHYS 212: Modern Physics
  • PHYS 310: Classical Mechanics
  • PHYS 314: Intermediate Laboratory
  • PHYS 340: Materials Physics
  • PHYS 351: Seminar in Modern Physics

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 University.
  • Another effect that I am particularly interested in, as a result of postdoctoral 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)  

Notes

  • Yumi Ijiri Publishes Article

    March 21, 2019

    Professor of Physics Yumi Ijiri recently published an article in Physical Review B titled "Correlated spin canting in ordered core-shell Fe3O4/MnxFe3-xO4 nanoparticle assemblies." The paper was co-authored with Oberlin students Ian Hunt-Isaak '17, Hillary Pan '17, and Jane Hsieh '20 and with other scientists at Carnegie Mellon University and the National Institute of Standards and Technology.

  • Yumi Ijiri Interviewed

    February 19, 2019

    Professor of Physics Yumi Ijiri was interviewed for a recent article in the Los Angeles Times, where Ijiri discussed the effects of the government shutdown on science, specifically at the NIST Center for Neutron Research.

  • Yumi Ijiri Presents and Chairs Session

    August 23, 2018

    Professor of Physics Yumi Ijiri gave two presentations on manganese ferrite nanoparticles and chaired a session at the International Conference on Magnetism, held in San Francisco, CA from July 15-20.  Oberlin students Jane Hsieh '20, Ian Hunt-Isaak '17, and Hillary Pan '17 were co-authors on the presentations, along with scientists from Carnegie Mellon University, the National Institute of Standards and Technology, and King Abdullah University of Science and Technology.

  • Yumi Ijiri Coauthors Article

    March 30, 2018

    Professor of Physics Yumi Ijiri coauthored an article, "Spin canting across core/shell Fe3O4/MnxFe3-xO4 nanoparticles," published in the journal Scientific Reports.  Ian Hunt-Isaak ’17 and Hillary Pan ’17, are coauthors, and the work was completed in collaboration with scientists at Carnegie Mellon University, Daresbury Laboratory, National Institute of Standards and Technology, University of Manitoba, and University of York.

  • Yumi Ijiri Awarded National Science Foundation Grant

    December 12, 2016

    Professor of Physics Yumi Ijiri was awarded a three-year, $225,000 grant from the National Science Foundation to support her project entitled "RUI:  Magnetic Morphologies and Excitations in Ferrite Nanoparticle Assemblies."  The grant will fund research into unusual magnetic arrangements that form in very small magnets.  Professor Ijiri and her students will make use of equipment at Oberlin and travel to the NIST Center for Neutron Research in Gaithersburg, MD to perform experiments.  The work will is in collaboration with scientists at Cambrian Technologies, Carnegie Mellon University, Case Western Reserve University, and NIST.

  • Yumi Ijiri Publishes Article in Physical Review B

    December 15, 2014

    Professor of Physics Yumi Ijiri recently published the article "Particle moment canting in CoFe2O4 Nanoparticles." The article appears in the journal Physical Review B (condensed matter and materials physics) as a Rapid Communication. Kathryn Hasz '14, now a graduate student at University of Pennsylvania, is the lead author, and the work was done in collaboration with scientists at the National Institute of Standards and Technology and Carnegie Mellon University.

  • Yumi Ijiri Co-Authors Article

    November 11, 2014

    Professor of Physics Yumi Ijiri recently co-authored an article, entitled "Origin of Surface Canting within Fe3O4 Nanoparticles." The article is published in the journal Physical Review Letters and has been selected as an Editors' Suggestion for that issue. Kathryn Hasz '14, currently a graduate student at the University of Pennsylvania, is also a co-author, and the work was done in collaboration with scientists at the National Institute of Standards and Technology, Carnegie Mellon University, and the Department of Energy.

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