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

High Resolution Image Download MS PowerPoint Slide This study presents the synthesis and magnetic characterization of two quaternary MAB phases: CrMn 4 SiB 2 and Mo 0.8 Mn 4.2 SiB 2 . 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 I 4/ mcm, with Mo demonstrating distinct site preferences in Mo 0.8 Mn 4.2 SiB 2 . Magnetic measurements indicate the presence of long-range ferromagnetic interactions, with Curie temperatures ( T C ) of approximately 270 K for CrMn 4 SiB 2 and 340 K for Mo 0.8 Mn 4.2 SiB 2 . Field-dependent magnetization measurements indicate a saturation magnetization ( M s ) of 5.128 μ B /f.u. (at 5 K) for CrMn 4 SiB 2 and 6.214 μ B /f.u. (at 5 K) and 3.692 μ B /f.u. (at 300 K) for Mo 0.8 Mn 4.2 SiB 2 . The introduction of Mo or Cr in the ternary parent compound Mn 5 SiB 2, opens a hysteresis for the first time in this class of T2 phases, with intrinsic coercivities of H c = 5.57 kA/m for CrMn 4 SiB 2 and 6.53 kA/m for Mo 0.8 Mn 4.2 SiB 2 . Density functional theory (DFT) calculations confirm the ferromagnetic ordering while the magnetocrystalline anisotropy energy (MAE) calculations show that CrMn 4 SiB 2 and MoMn 4 SiB 2 have in-plane anisotropy with higher MAE values than Mn 5 SiB 2, thus confirming experimental findings. This research not only introduces a synthesis pathway toward single-phase T2-based quaternary materials, but it also opens an avenue toward MAB-based permanent magnets.