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Detection of Ferromagnetic Dynamics Using NV Centers in Diamond

McCullian, Brendan Andrew
http://rave.ohiolink.edu/etdc/view?acc_num=osu1585664864822124

Abstract Details

2020, Doctor of Philosophy, Ohio State University, Physics.
Magnetic resonance is a powerful technique for detection and manipulation of spin dynamics. Resonance techniques are used in medical settings to non-invasively image patients in real time. In biology and chemistry settings resonance can be used to detect the local environment of spins which can reveal molecular structure and function. For condensed matter physicists the resonant response of novel materials can give insight about the underlying magnetic interactions by using the spins inside the sample as a probe of the local environment. My work focuses on using the nitrogen-vacancy defect center (NV center) in diamond to detect magnetic noise from nearby ferromagnetic thin films. NV centers enable optical detection of magnetic dynamics with nanoscale spatial resolution owing to their spin dependent fluorescence, high sensitivity to magnetic fields and atomic scale size. Ferromagnets are used in many applications like microwave resonators and filters owing to their wide frequency tunability with magnetic field. The damping parameter describes the relaxation of microwave-driven ferromagnetic samples and is akin to the quality factor of the ferromagnet as a resonator. Understanding the microscopic damping processes is in general challenging, but the application of NV centers to study magnetic field noise from nearby ferromagnetic layers can give valuable insight about the damping mechanisms. Magnetic field fluctuations associated with the damping processes in ferromagnets create stray dipolar fields which can couple to and relax nearby NV defects, allowing for local measurement of the ferromagnetic noise spectrum. I used NV centers to study the damping process in an organic magnetic sample vanadium tetracyanoethylene, a material of significant applications interest for its extremely low damping in combination with deposition on diverse substrates. We found that the magnon spectrum in this material is quite different than conventional low damping materials, which can have significant effect on the real space wavelength of magnons for applications. We also studied a low-damping insulating ferrimagnet nickel zinc aluminum ferrite which turned out to be an excellent platform for studying nonlinear ferroamgnetic dynamics. Our NV measurements of the NV response to the ferromagnetic resonance in the ferrite showed the first demonstration of pairs of magnons coupling to and relaxing nearby NV centers, a result which suggests that the NV can be used to sense ferromagnetic dynamics at considerably higher frequencies than has been previously shown. During my research I designed and developed a scanned probe based NV diamond microscope for nanoscale magnetic detection and imaging. With the hope of applying the NV relaxometry technique to higher frequencies, I carried out resonance spectroscopy characterization of a few novel ferromagnetic materials. Going forward these measurements can be used to select materials as a proving ground for the two-magnon relaxometry technique. We also spent considerable time studying magnetic skyrmion defects in chiral magnetic thin films with resonance technique, which should be an excellent application of our scanned probe NV microscope.
P. Chris Hammel (Advisor)
Fengyuan Yang (Committee Member)
Tin-Lun Ho (Committee Member)
Amy Connolly (Committee Member)
172 p.
Physics
NV center; magnon; magnetic resonance; ferromagnetic resonance; FMR; relaxometry; damping; resonance spectroscopy; spin wave; spinwave

Recommended Citations

Citations

  • McCullian, B. A. (2020). Detection of Ferromagnetic Dynamics Using NV Centers in Diamond [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1585664864822124

    APA Style (7th edition)

  • McCullian, Brendan. Detection of Ferromagnetic Dynamics Using NV Centers in Diamond. 2020. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1585664864822124.

    MLA Style (8th edition)

  • McCullian, Brendan. "Detection of Ferromagnetic Dynamics Using NV Centers in Diamond." Doctoral dissertation, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1585664864822124

    Chicago Manual of Style (17th edition)

osu1585664864822124
172
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This open access ETD is published by The Ohio State University and OhioLINK.