Material Processing‐Driven Evolution of Magnetic Hardening and Magnetoresistance in Mn _1.1 Zn _0.9 Sb _0.9 Bi _0.1 Compounds

We report the impact of mechanical processing on the structural, magnetic, and magnetotransport properties of Mn 1.1 Zn 0.9 Sb 0.9 Bi 0.1 . Samples synthesized in the as‐cast bulk (ACB) form were subsequently processed into powder (PWDR) and cold‐pressed pellet (CPP) states to investigate microstructure–property correlations. Temperature‐dependent X‐ray diffraction reveals no structural phase transition down to 5 K, confirming that the pronounced magnetic hardening originates purely from processing‐induced microstructural modifications and crystallographic textures formation. A remarkable enhancement of coercivity is observed, increasing from ≈300 Oe in the ACB state to ≈4.8 kOe in the CPP sample at 5 K (≈1500% enhancement), which is attributed to heterogeneous microstructural features and domain wall pinning by inhomogeneously distributed residual Bi impurities. Magnetotransport measurements further reveal a systematic suppression of magnetoresistance from ≈16% (ACB) to ≈1.5% (CPP) at 5 T, driven by enhanced grain boundary scattering and reduced carrier mean free path. These results demonstrate that simple mechanical processing provides an effective route to engineer coercivity and magnetoresponsive properties in Mn 2 Sb‐based systems, offering potential pathways for a low‐cost, high‐performance design strategy for permanent magnet applications.