Materials Science and Engineering Colloquium
Date: October 24, 2014 from 11:00 am to 12:00 pm EDT
Location: Columbia University, Morningside Campus
S.W. Mudd, Room 214
Contact: For further information regarding this event, please contact APAM Department by sending email to or by calling 212-854-4457.
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Fengyuan Yang
Ohio State University

"Pure spin transport in nonmagnetic, ferromagnetic and antiferromagnetic materials using YIG-based heterostructures"

A central focus of spintronics is the generation and transmission of spin currents mediated by itinerant charges or magnetic excitations. In recent years, pure spin currents generated by ferromagnetic resonance spin pumping or thermal gradients have attracted wide interests because of the potential for energy-efficient, spin-based electronics without the need of an accompanying charge current. In addition, ferromagnetic resonance spin pumping is a powerful technique for understanding the spin Hall effect in a broad range of materials. In this talk, we will discuss our recent results on pure spin transport in several classes of materials with different magnetic structures, including nonmagnetic metals [1-3], ferromagnetic metals [4], nonmagnetic insulators [5], and antiferromagnetic insulators [6] using Y3Fe5O12 (YIG) based spin pumping. The spin Hall angles determined for a series of 3d, 4d, and 5d transition metals show that both atomic number and d-electron count play important roles in spin Hall physics [2, 3]. We observe robust spin transport from YIG to Pt across antiferromagnetic insulators up to 100 nm thickness [6], in clear contrast to the angstrom-scale exponential decay of spin currents across nonmagnetic insulator spacers [5]. Surprisingly, the spin current is significantly enhanced by the insertion of a thin antiferromagnetic layer between YIG and Pt. This demonstrates highly efficient spin transport through an AF insulator carried by magnetic excitations.


[1].    Wang, et al. Phys. Rev. B 88, 100406(R) (2013).
[2].    Wang, et al. Phys. Rev. Lett. 112, 197201 (2014).
[3].    Du, et al. arXiv: 1410.1590.
[4].    Wang, et al. Appl. Phys. Lett. 104, 202405 (2014).
[5].    Du, et al. Phys. Rev. Lett. 111, 247202 (2013).
[6].    Wang, et al. Phys. Rev. Lett. 113, 097202 (2014).

Host: William Bailey