Observation of disorder-driven dramatic enhancement of magnetic moment and giant magnetoresistance in a half-metallic Heusler nanoalloy

Abstract

Recognizing the influence of disorder on physical characteristics at the nanoscale is crucial. We report an integrated experimental and computational study of disorder effects on the electronic, magnetic, and transport properties of Co2FeAl nanoalloy for room-temperature spintronics. The sample crystallizes in its A2 disordered phase. The observed enhancement in Curie temperature (Tc ∼ 1262 K) and saturation magnetization (Ms ∼ 6.5 μB/f.u.), which exceeds Slater–Pauling rule predictions, is attributed to the influence of structural disorder. Detailed resistivity analysis (7–300 K) suggests the half-metallic nature of Co2FeAl. Interestingly, it also exhibits giant magnetoresistance at room temperature. Given the high Tc, Co2FeAl could be a favorable material for spin-polarized electron sources. First-principles calculations confirm the weak spin-polarized half-metallic nature, consistent with experimental results. Simulations of electronic structures and disorder-dependent magnetic moments support the findings. The co-occurrence of these properties makes Co2FeAl nanoalloy a promising candidate for future technological advancements.