Effects of Fe deficiency and Co substitution in polycrystalline and single crystals of Fe${}_3$GeTe${}_2$

Abstract

Fe${}_3$GeTe${}_2$ is a two-dimensional van der Waals material with a ferromagnetic ground state and a maximum transition temperature $T_{\mathrm{c}}\sim 225$ K. However, when Fe${}_3$GeTe${}_2$ is synthesized lower values of $T_{\mathrm{c}}$ are often reported. This is attributed to a deficiency in the Fe at the 2c site in the crystal structure. Here we investigate the effect of Fe deficiency and the substitution of Co for Fe on the magnetic properties of this system. We have synthesized both polycrystalline material and single crystals by chemical vapor transport and the flux method, with the largest crystals obtained using the flux method. Cobalt substitution at the Fe site is found to significantly reduce the magnetic transition temperature. Crystals of Fe${}_3$GeTe${}_2$ grown by chemical vapor transport with $\sim 8\%$ excess Fe in the starting materials display an optimum Fe content and magnetic transition temperature.

arXiv comment22 pages, 8 figures, 3 tables. Published online in ACS Crystal Growth and Design

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Cited by in corpus (3)

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• Quenching the Non-Collinear Spin Order in High-Tc Layered Ferromagnet Fe5GeTe2
• Two-Dimensional Magnetic Materials from Ferromagnetism to Altermagnetism: Fabrication, Symmetry, Evidence, and Device Readiness