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arXiv · 1808.05741

Magnetic and structural studies of G-phase compound Mn$_6$Ni$_{16}$Si$_7$

S. J. Ahmed·J. E. Greedan·C. Boyer·M. Niewczas
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Abstract

Transition metal compounds with complex crystal structures tend to demonstrate interesting magnetic coupling resulting in unusual magnetic properties. In this work, the structural and magnetic characterization of a single crystal of the Ni-Mn-Si based G-phase compound, Mn$_6$Ni$_{16}$Si$_7$, grown by the Czochralski method, is reported. In this structure isolated octahedral Mn$_6$ clusters form a f.c.c. lattice. As each octahedron consists of eight edge-sharing equilateral triangles, the possibility for geometric frustration exists. Magnetization and specific heat measurements showed two magnetic phase transitions at 197 K and 50 K, respectively. At 100 K neutron diffraction on powder samples shows a magnetic structure with k = (001) in which only four of the six Mn spins per cluster order along $<100>$ directions giving a two dimensional magnetic structure consistent with intra-cluster frustration. Below the 50 K phase transition the Mn spins cant away from $<100>$ directions and a weak moment develops on the two remaining Mn octahedral sites.

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S. J. Ahmed, J. E. Greedan, C. Boyer, M. Niewczas. 2018-08-17. Magnetic and structural studies of G-phase compound Mn$_6$Ni$_{16}$Si$_7$. https://doi.org/10.1021/acs.inorgchem.8b01964

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