Large anomalous Nernst and inverse spin-Hall effects in epitaxial thin films of kagome semimetal Mn₃Ge

Journal Article · Fri Sep 11 00:00:00 EDT 2020 · Physical Review Materials

DOI:https://doi.org/10.1103/physrevmaterials.4.094201· OSTI ID:1674980

Hong, Deshun ^[1]; Anand, Naween ^[1]; Liu, Changjiang ^[1]; Liu, Haihua ^[2]; Arslan, Ilke ^[2]; Pearson, John E. ^[1]; Bhattacharya, Anand ^[1]; Jiang, J. S. ^[1]

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1. Argonne National Lab. (ANL), Argonne, IL (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials

Synthesis of crystallographically well-defined thin films of topological materials is important for unraveling their mesoscale quantum properties and for device applications. ${\mathrm{Mn}}_3\mathrm{Ge}$, an antiferromagnetic Weyl semimetal with a chiral magnetic structure on a kagome lattice, is expected to have enhanced Berry curvature around Weyl nodes near the Fermi energy, leading to large anomalous Hall/Nernst effects and a large spin-Hall effect. Using magnetron sputtering, we have grown epitaxial thin films of hexagonal $\mathrm{D}{0}_{19}{\mathrm{Mn}}_3\mathrm{Ge}$ that are flat and continuous. Large anomalous Nernst and inverse spin-Hall effects are observed in thermoelectric and spin-pumping devices. The anomalous Nernst signal in our ${\mathrm{Mn}}_3\mathrm{Ge}$ films is estimated to be 0.1 μV/K and is comparable to that in ferromagnetic Fe, despite ${\mathrm{Mn}}_3\mathrm{Ge}$ having a weak magnetization of $~3.5\mathrm{m}{\mu }_{\mathrm{B}}/\mathrm{Mn}$ at room temperature. In this work, the spin-mixing conductance is $90.5{\mathrm{nm}}^{–2}$ at the $\mathrm{Py}/{\mathrm{Mn}}_3\mathrm{Ge}$ interface, and the spin-Hall angle in ${\mathrm{Mn}}_3\mathrm{Ge}$ is estimated to be about eight times of that in Pt.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Energy Frontier Research Centers (EFRC) (United States). Center for the Advancement of Topological Semimetals (CATS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1674980
• Journal Information: Physical Review Materials, Vol. 4, Issue 9; ISSN 2475-9953
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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