Enhanced hard magnetic properties in partially-doped Mn3−xGdxGa (x ⩽ 0.03)

Abstract

Abstract The effect of partial (1–3%) rare-earth Gadolinium doping in D 0 22 Mn 3 Ga hard magnet has been investigated in this work. The Mn 3 Ga undergoes magnetic transition at T c ∼ 745 K, which decreases down to T c ∼ 715 K upon 1% Gd-doping with introduction of mixed Mn valence states, as revealed from XPS study. The hard magnetic behavior of Mn 3 Ga has been observed in a wide temperature range (up to T c ). More importantly, the partial Gd-doping significantly enhances the room temperature hard magnetic properties i.e. squareness ratio ( m r / m s ), coercivity ( H c ) and energy product ( BH max ) from 0.43, 2.73 kOe and 0.39 MGOe ( Mn 3 Ga ) to 0.57, 4.25 kOe and 0.5 MGOe ( Mn 2.97 Gd 0.03 Ga ), respectively. The modified Stoner-Wohlfarth model and low-field minor loop analysis reveal the nucleation hardening mechanism for the magnetization reversal. The study proposes the partial rare-earth doping as a new approach to enhance the hard magnetic properties of rare-earth free hard magnets.