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Sub-Terahertz Spin Pumping from an Insulating Antiferromagnet

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Date Issued:
2019
Abstract/Description:
The combination of the spin transfer torque and spin Hall effects, or their reciprocal dynamical spin pumping and inverse spin Hall effects, respectively, enable reading and controlling the magnetization state in spintronics devices which are at the verge of mass commercialization as the next generation of energy-efficient and fast magnetic random-access memory applications with the use of ferromagnetic elements, e.g., the spin valve. However, these effects have remained elusive in antiferromagnetic-based devices up to date, despite the fascinating advantages offered by the absence of stray fields (zero net magnetization), Terahertz spin dynamics, and the widespread availability of metallic, insulating and semiconducting antiferromagnetic materials. In this thesis I report the first demonstration of sub-Terahertz dynamical spin pumping at the interface between an antiferromagnet and a non-magnetic material; more specifically a uniaxial insulating antiferromagnet MnF2 and heavy metal Pt. The measured ISHE signal generated by the corresponding spin-charge current interconversion in the platinum layer is modulated by the handedness of the circularly polarized sub-THz irradiation. This effect results directly from the opposite chirality of each of the fundamental dynamical modes of the antiferromagnet. Contrary to the case of ferromagnets, this observation in an antiferromagnetic system allows unambiguously differentiating coherent spin pumping from incoherent spin Seeback effect, by which electric signals result from thermal activation. A complete study of the generated electric signals at the antiferromagnetic resonances, the spin-flop mode and the transition between the two regimes as the microwave polarization is continuously varied from circular to linear polarizations enabled an understanding of the different phenomena governing interconversion of spin dynamics and charge currents at the MnF2/Pt interface.
Title: Sub-Terahertz Spin Pumping from an Insulating Antiferromagnet.
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Name(s): Vaidya, Priyanka, Author
Del Barco, Enrique, Committee Chair
Neupane, Madhab, Committee Member
Nakajima, Yasuyuki, Committee Member
Hernandez, Florencio, Committee Member
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2019
Publisher: University of Central Florida
Language(s): English
Abstract/Description: The combination of the spin transfer torque and spin Hall effects, or their reciprocal dynamical spin pumping and inverse spin Hall effects, respectively, enable reading and controlling the magnetization state in spintronics devices which are at the verge of mass commercialization as the next generation of energy-efficient and fast magnetic random-access memory applications with the use of ferromagnetic elements, e.g., the spin valve. However, these effects have remained elusive in antiferromagnetic-based devices up to date, despite the fascinating advantages offered by the absence of stray fields (zero net magnetization), Terahertz spin dynamics, and the widespread availability of metallic, insulating and semiconducting antiferromagnetic materials. In this thesis I report the first demonstration of sub-Terahertz dynamical spin pumping at the interface between an antiferromagnet and a non-magnetic material; more specifically a uniaxial insulating antiferromagnet MnF2 and heavy metal Pt. The measured ISHE signal generated by the corresponding spin-charge current interconversion in the platinum layer is modulated by the handedness of the circularly polarized sub-THz irradiation. This effect results directly from the opposite chirality of each of the fundamental dynamical modes of the antiferromagnet. Contrary to the case of ferromagnets, this observation in an antiferromagnetic system allows unambiguously differentiating coherent spin pumping from incoherent spin Seeback effect, by which electric signals result from thermal activation. A complete study of the generated electric signals at the antiferromagnetic resonances, the spin-flop mode and the transition between the two regimes as the microwave polarization is continuously varied from circular to linear polarizations enabled an understanding of the different phenomena governing interconversion of spin dynamics and charge currents at the MnF2/Pt interface.
Identifier: CFE0007870 (IID), ucf:52776 (fedora)
Note(s): 2019-12-01
Ph.D.
Sciences,
Doctoral
This record was generated from author submitted information.
Subject(s): Spintronics -- Antiferromagnets -- Antiferromagnetic Resonance -- Spin Pumping -- ISHE -- TeraHertz Dynamics -- Polarized Microwaves
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0007870
Restrictions on Access: public 2019-12-15
Host Institution: UCF

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