PhD Mid-term Seminar Series: Detection of Magnon Currents in EuS

CIC nanoGUNE Seminars

Montserrat Xochitl Aguilar, Pre-doctoral Researcher, Nanodevices
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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PhD Mid-term Seminar Series: Detection of Magnon Currents in EuS **Detection of Magnon Currents in EuS** Montserrat Xochitl Aguilar Pre-doctoral Researcher, Nanodevices Magnons, the quanta of spin wave excitations in magnetic systems, allow for the transport of spin angular momentum through magnetic compounds, including insulators. The ability to control the injection, propagation, and detection of such magnon spin currents represents an asset for the progress of spintronics. So far, magnon transport have been studied mainly through Y3Fe5O12 (YIG) and a few other ferri- and antiferromagnetic insulators [1], while there exist many materials in which their behavior is little-known. Here, we study for the first time the generation of thermal magnon currents in 18-nm-thick films of the ferromagnetic insulator europium sulfide (EuS), which exhibits a Curie temperature around Tc = 19 K [2]. We perform non-local (NL) transport measurements using Pt electrodes, with different separation distances d, as magnon injectors and detectors. We study the NL voltage, generated at the detector due to the inverse spin Hall effect (ISHE), depending on the in-plane angle between the sample magnetization and the polarization direction of the spins induced by ISHE in the Pt, for the temperature range 2 K < T < 30 K. The second harmonic component of the NL voltage indicates that thermal magnon currents generated in the injector flow to the detector for distances ranging from d = 0.8 mm up to d = 2 mm and for temperatures T < 20 K. By analyzing the length dependence of the second harmonic signal we evaluate the magnon propagation length in the EuS films, which we find to be relatively short, as compared to the YIG case. We discuss our results considering the Gilbert damping and the Curie temperature of the EuS films. **References ** [1] A. Brataas et al., Physics Reports **885** , 1 (2020). [2] J. M. Gómez-Pérez et al., Nano Letters **20** , 6815 (2020).