Regensburg 2022 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Magnonics 1

MA 13.5: Vortrag

Dienstag, 6. September 2022, 10:30–10:45, H43

A bifold theoretical approach to spin transport in 2D easy axis and easy plane antiferromagnets — •Verena Brehm and Alireza Qaiumzadeh — QuSpin, NTNU Trondheim, Norway

Due to their terahertz excitation spectrum and the absence of stray fields, antiferromagnetic insulators are great candidates for magnonic applications [1].

We model an antiferromagnet with homogenous DMI inspired by hematite α-Fe₂O₃, that undergoes two phase transitions: For very low temperatures, there is no magnetization as the Néel vector lies in the plane, which corresponds to an easy axis anisotropy. At the Morin temperature, the Néel vector rotates out of plane, leading to a finite DMI-induced magnetization with the system being in an easy plane phase, until at the Néel temperature magnetic order is lost. Spin transport measurements across the Morin temperature [2] are exciting, since the magnonic modes show an anisotropy-dependent polarization [3], which has an impact on the transported angular momentum [4].

In this talk, we demonstrate both analytically and numerically (micromagnetic simulations [5]), how the magnon polarization impacts the spin transport signal across the Morin transition, in connection to Néel vector dynamics and dispersion relation analysis.

[1] Rezende, White. Phys. Rev. B 14 (1976)

[2] Ross et al. J. Mag. Magn. Mat. 453 (2022); arXiv:2106.12853

[3] Rezende et al. J. Appl. Phys. 126 (2019)

[4] Lebrun, Kl'aui et al. Nat. Comm. 11 6332 (2020)

[5] Lepadatu. J. Appl. Phys. 128 243902 (2020)