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Manipulation of Magnetization Dynamics in Ferromagnetic and Antiferromagnetic Heterostructures

Cheng, Yang
http://rave.ohiolink.edu/etdc/view?acc_num=osu1619562779910017

Abstract Details

2021, Doctor of Philosophy, Ohio State University, Physics.
Spintronics is a vibrant research field that studies and utilizes the intrinsic spin properties of electrons in various materials. The dual states of spin (spin-up and spin-down) make it a natural candidate to represent the bit “0” or “1” in data storage and information processing. In the past two decades, a series of important discoveries in spintronics has been made in the labs and brought into the market. My research focus is to identify and investigate novel ferromagnetic and antiferromagnetic heterostructures that can be used to powerfully manipulate spins. This thesis is organized as follows: In Chapters 1 and 2, I briefly introduce the background knowledge in spintronics and the experimental as well as theoretical techniques that I use in my research. From Chapter 3 to 7, I present five research projects that I lead in my graduate study. In Chapter 3, we study a new nonlocal spin transport scheme. Compared with conventional nonlocal spin transport geometry where the spin current is generated through a ferromagnetic injector or spin Hall effect, in our scheme, spin current generation is through ferromagnetic resonance spin pumping in lateral Pt/Y3Fe5O12 heterostructures. This avoids the generation of high-energy thermal magnons through the spin Seebeck effect. We also observe a high spin current injection, which is more than 20 times larger than the local spin pumping in Pt/Y3Fe5O12, suggesting that the ultra-low damping bare Y3Fe5O12 is a much more efficient spin pumping source; In Chapter 4, we study the spin current transportation in Pt/NiO/Y3Fe5O12 trilayers through angular dependent ferromagnetic resonance spin pumping measurements. By systematically varying the temperatures and thicknesses of NiO, we observe spin current transport that is mediated by the antiferromagnetic NiO interlayer, which gives a non-sinusoidal angular dependence of inverse spin Hall voltage; In Chapter 5, we study current-induced Neel order switching in antiferromagnetic heterostructure Pt/α-Fe2O3. We demonstrate that the detected Hall resistance change is indeed due to the Neel order switching by carefully ruling out the thermal artifact from Pt. Our results point to a promising path toward controlling antiferromagnets using spin-orbit torque; In Chapter 6, we study the harmonic Hall response experimentally and theoretically in antiferromagnetic heterostructure Pt/α-Fe2O3. We build a theoretical model that proves the current-induced effects in antiferromagnetic heterostructures can be also detected by harmonic Hall technique like previously demonstrated in ferromagnetic heterostructures. Our experimental measurement is in excellent agreement with our modeling, which points out the important role played by the magnetoelastic effect and spin-orbit torque in current-induced switching of antiferromagnets; In Chapter 7, we make Hall measurements in antiferromagnetic heterostructure Pt/Cr2O3 bilayers and observe the high-temperature topological Hall effect. This indicates the nontrivial topological spin texture at Pt/Cr2O3 interface, which gives insights in searching skyrmions in antiferromagnets. The last chapter is a conclusion of the entire thesis.
Fengyuan Yang (Advisor)
Jay Gupta (Committee Member)
Andrew Heckler (Committee Member)
Yuanming Lu (Committee Member)
Physics
Spintronics

Recommended Citations

Citations

  • Cheng, Y. (2021). Manipulation of Magnetization Dynamics in Ferromagnetic and Antiferromagnetic Heterostructures [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619562779910017

    APA Style (7th edition)

  • Cheng, Yang. Manipulation of Magnetization Dynamics in Ferromagnetic and Antiferromagnetic Heterostructures. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1619562779910017.

    MLA Style (8th edition)

  • Cheng, Yang. "Manipulation of Magnetization Dynamics in Ferromagnetic and Antiferromagnetic Heterostructures." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619562779910017

    Chicago Manual of Style (17th edition)

osu1619562779910017
178
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