Opening the Hysteresis Loop in MAB Magnets: Experimental and Computational Studies of CrMn4SiB2 and Mo0.8Mn4.2SiB2

Shola E. Adeniji; Alexei A. Belik; Takao Mori; Boniface P. T. Fokwa

doi:10.1021/acs.chemmater.5c00187

Article Opening the Hysteresis Loop in MAB Magnets: Experimental and Computational Studies of CrMn₄SiB₂ and Mo_0.8Mn_4.2SiB₂

Shola E. Adeniji ; Alexei A. Belik (National Institute for Materials Science) ; Takao Mori (National Institute for Materials Science) ; Boniface P. T. Fokwa

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Shola E. Adeniji, Alexei A. Belik, Takao Mori, Boniface P. T. Fokwa. Opening the Hysteresis Loop in MAB Magnets: Experimental and Computational Studies of CrMn₄SiB₂ and Mo_0.8Mn_4.2SiB₂. Chemistry of Materials. 2025, 37 (6), 2349-2357. https://doi.org/10.1021/acs.chemmater.5c00187

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This study presents the synthesis and magnetic characterization of two new quaternary MAB phases: CrMn4SiB₂ and Mo0.8Mn4.2SiB2. Using a refined synthesis method, we successfully produced single-phase compounds, overcoming previous challenges associated with impurity phases. Both compounds crystallize in the tetragonal space group I4/mcm, with Mo demonstrating distinct site preferences in Mo0.8Mn4.2SiB2. Magnetic measurements indicate the presence of long-range ferromagnetic interactions, with Curie temperatures (TC) of approximately 270 K for CrMn4SiB₂ and 340 K for Mo0.8Mn4.2SiB2. Field-dependent magnetization measurements indicate a saturation magnetization (Ms) of 5.128 μB/f.u. (at 5 K) for CrMn4SiB₂ and 6.214 μB/f.u. (at 5 K) and 3.692 μB/f.u. (at 300 K) for Mo0.8Mn4.2SiB2. The introduction of Mo or Cr in the ternary parent compound Mn5SiB2, opens a hysteresis for the first time in this class of T2 phases, with intrinsic coercivities of Hc = 5.57 kA/m for CrMn4SiB₂ and 6.53 kA/m for Mo0.8Mn4.2SiB2. DFT calculations confirm the ferromagnetic ordering while the magnetocrystalline anisotropy energy (MAE) calculations show that CrMn4SiB2 and MoMn4SiB2 have in-plane anisotropy with higher MAE values than Mn5SiB2, thus confirming experimental findings. This research not only introduces a new synthesis pathway toward single-phase T2-based quaternary materials, but it also opens a new avenue toward MAB-based permanent magnets.

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