Helical spin ordering in room-temperature metallic antiferromagnet Fe3Ga4

Abstract

Metallic Fe3Ga4 displays a complex magnetic phase diagram that supports an intermediate antiferromagnetic (AFM) helical spin structure (HSS) state at room temperature which lies between two ferromagnetic (FM) phases. Magnetic measurements along the three crystallographic axes were performed in order to develop a model for the temperature and field dependence of the HSS state. These results show that the AFM state is a helically ordered spiral propagating along the c-axis with the magnetic moments rotating in the ab-plane. Under applied magnetic field, the AFM state exhibits a metamagnetic transition to conical ordering before entering a fully field-polarized FM state at high fields. The conical ordering in the AFM state is anisotropic even within the ab-plane and may gives rise to Berry phase effects in transport measurements. Metallic conductivity from density of states computations was confirmed through resistivity measurements and no anomalous behavior was observed through the various magnetic transitions.