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Spin Transport in Magnetic Insulators.

Chen, Yizhang.

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Spin Transport in Magnetic Insulators.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Spin Transport in Magnetic Insulators./
作者:	Chen, Yizhang.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
面頁冊數:	115 p.
附註:	Source: Dissertations Abstracts International, Volume: 80-10, Section: B.
Contained By:	Dissertations Abstracts International80-10B.
標題:	Applied physics. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13420488
ISBN:	9781392004524

Spin Transport in Magnetic Insulators.
Chen, Yizhang.

Spin Transport in Magnetic Insulators. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 115 p.

Source: Dissertations Abstracts International, Volume: 80-10, Section: B.

Thesis (Ph.D.)--New York University, 2019.

This item must not be sold to any third party vendors.

The field of spintronics, or spin electronics, is based upon the active manipulation of the spin degree of freedom in solid-state systems. The dynamics of spin relaxation, generation of spin polarization, and spin transport have prominent impacts on spintronics. Conventional studies and applications of magnetism are centered around transition metals (e. g. iron, nickel, cobalt) or the properties of their alloys (e. g. permalloy, NbFeB). However, some of the most recent advances in spintronics are based upon magnetic insulators, and have important future applications. These include the long-range spin transport through ferromagnetic insulators, spin superfluidity, the spin Seebeck/Peltier effects, and antiferromagnetic spin valves. In this thesis, I present our studies of spin transport in magnetic insulators, including the study of a collective spin-reversal phenomenon in a single crystal of a single molecule magnet (SMM), the spin Seebeck effect in a ferromagnetic insulator/normal metal bilayer and spin transport in an all-insulating spin valve. The first part of my thesis involves the study of spontaneous magnetic deflagration, a self-propagating spin-reversal front in a single crystal of SMMs. SMMs are a class of metal-organic compounds consisting of a magnetic cluster surrounded by organic ligands. Individual molecules inside a single crystal are almost identical with a relatively large ground-state spin and a strong uniaxial anisotropy. Molecules inside SMMs interact weakly through the magnetic dipole fields or lattice vibrations (e. g. phonons). SMMs exhibit both classical and quantum properties, making them ideal candidates for studying mesoscopic phenomena. The dynamics of magnetic relaxation and collective spin reversal were investigated. When spins initially prepared in metastable states reverse, Zeeman energy is released. When the released energy cannot diffuse away rapidly, a thermal instability can lead to a self-sustained propagating spin-reversal front. Ignition onsets and the speed of spontaneous magnetic deflagration were studied by sweeping a magnetic field transverse to the easy axis and conducting local time-resolved magnetic measurements. The second part of the thesis was focused on the study of thermally generated spin currents in a ferromagnetic insulator. Spin Seebeck effect (SSE) denotes the generation of spin currents when a ferromagnet is subject to a temperature gradient. Harmonic measurements were performed to investigate the generation and transport of spin currents carried by magnons in the ferromagnetic insulator. A non-magnetic metal with strong spin-orbit coupling was used to convert a spin current into a charge current. Both linear and non-linear responses were studied in the system, revealing the thermal origin of the signal. In addition, a new technique with was developed to detect the SSE. A spin valve is a spin-based device who properties depend on the relative magnetization orientations of the magnetic layers. We studied the spin transport properties of an insulating spin valve, which consists of an antiferromagnetic insulator sandwiched between two ferromagnetic insulators (YIG/NiO/YIG). The SSE of the system was investigated in a broad range of temperature. The spin diffusion length of the antiferromagnetic insulator was characterized. Interestingly, the SSE signals display a significant enhancement at low temperature, indicating a strong correlation between SSE and the magnetization of the ferromagnetic insulators.

ISBN: 9781392004524Subjects--Topical Terms:

3343996
Applied physics.

Spin Transport in Magnetic Insulators.
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