Sub-Terahertz Spin Pumping from an Insulating Antiferromagnet
CIC nanoGUNE Seminars
- Speaker
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Enrique del Barco, University of Central Florida
- When
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2020/02/11
17:00 - Place
- CFM Auditorium
- Add to calendar
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iCal
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**Sub-Terahertz Spin Pumping from an Insulating Antiferromagnet**
Enrique del Barco
Physics Department, University of Central Florida, Orlando, Florida 32816, USA
Emerging phenomena, such as the spin-Hall effect (SHE), spin pumping, and
spin-transfer torque (STT), allow for interconversion between charge and spin
currents and the generation of magnetization dynamics that could potentially
lead to faster, denser, and more energy efficient, non-volatile memory and
logic devices. Present STT-based devices rely on ferromagnetic (FM) materials
as their active constituents. However, the flexibility offered by the
intrinsic net magnetization and anisotropy for detecting and manipulating the
magnetic state of ferromagnets also translates into limitations in terms of
density (neighboring elements can couple through stray fields), speed
(frequencies are limited to the GHz range), and frequency tunability (external
magnetic fields needed). A new direction in the field of spintronics is to
employ antiferromagnetic (AF) materials. In contrast to ferromagnets, where
magnetic anisotropy dominates spin dynamics, in antiferromagnets spin dynamics
are governed by the interatomic exchange interaction energies, which are
orders of magnitude larger than the magnetic anisotropy energy, leading to the
potential for ultrafast information processing and communication in the THz
frequency range, with broadband frequency tunability without the need of
external magnetic fields.
I will present the first evidence of sub-terahertz dynamical spin pumping at
the interface of a uniaxial insulating antiferromagnet MnF2 and platinum thin
films, measured by the ISHE voltage signal arising from spin-charge conversion
in the platinum layer. The ISHE signal depends on the chirality of the
dynamical modes of the antiferromagnet, which is selectively excited and
modulated by the handedness of the circularly polarized sub-THz irradiation
(see figure). Contrary to the case of ferromagnets, antiferromagnetic spin
pumping exhibits a sign dependence on the chirality of dynamical modes,
allowing for the unambiguous distinction between coherent spin pumping and the
thermally-driven, chirality-independent spin Seebeck effect. Our results open
the door to the controlled generation of coherent pure spin currents with
antiferromagnets at unprecedented high frequencies.
**Host:** F. Casanova