Magnetic structure determination of rare-earth based, high moment, atomic laminates; potential parent materials for 2D magnets

Abstract

We report muon spin rotation ($\mu$SR) and neutron diffraction on the rare-earth based magnets (Mo${}_{2/3}$RE${}_{1/3}$)${}_2$AlC, also predicted as parent materials for 2D derivatives, where RE = Nd, Gd (only ($\mu$SR), Tb, Dy, Ho and Er. By crossing information between the two techniques, we determine the magnetic moment ($m$), structure, and dynamic properties of all compounds. We find that only for RE = Nd and Gd the moments are frozen on a microsecond time scale. Out of these two, the most promising compound for a potential 2D high ($m$) magnet is the Gd variant, since the parent crystals are pristine with $m=6.5\pm 0.5{\mu }_B$, Néel temperature of $29\pm 1$ K, and the magnetic anisotropy between in and out of plane coupling is smaller than $10^{-8}$. This result suggests that magnetic ordering in the Gd variant is dominated by in-plane magnetic interactions and should therefore remain stable if exfoliated into 2D sheets.

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