Mn5Si3 Nanoparticles: Synthesis and Size-Induced Ferromagnetism.

Das, Bhaskar; Balasubramanian, Balamurugan; Manchanda, Priyanka; Mukherjee, Pinaki; Skomski, Ralph; Hadjipanayis, George C; Sellmyer, David J · Nano Lett · 2016

basic_science · Level V

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Abstract

Mn-based silicides are fascinating due to their exotic spin textures and unique crystal structures, but the low magnetic ordering temperatures and/or small magnetic moments of bulk alloys are major impediments to their use in practical applications. In sharp contrast to bulk Mn5Si3, which is paramagnetic at room temperature and exhibits low-temperature antiferromagnetic ordering, we show ferromagnetic ordering in Mn5Si3 nanoparticles with a high Curie temperature (Tc ≈ 590 K). The Mn5Si3 nanoparticles have an average size of 8.6 nm and also exhibit large saturation magnetic polarizations (Js = 10.1 kG at 300 K and 12.4 kG at 3 K) and appreciable magnetocrystalline anisotropy constants (K1 = 6.2 Mergs/cm(3) at 300 K and at 12.8 Mergs/cm(3) at 3 K). The drastic change of the magnetic ordering and properties in the nanoparticles are attributed to low-dimensional and quantum-confinement effects, evident from first-principle density-functional-theory calculations.