Magnetism and transport properties of metamagnetic Mn1−xCrxAu2

Crystallographic, magnetic and electric properties of metamagnetic Mn1−xCrxAu2 were studied. Pure MnAu2 has a helical-spin structure and the structure changes to a ferromagnetic state below the Néel temperature TN (∼360 K) and above a threshold magnetic field Hth (∼10 kOe at 300 K). The TN, Hth for the metamagnetic transition, and the helical angle of the helical-spin configuration decreases as the Cr content x increases. The Cr substitution seems to dilute the magnetism of MnAu2 and to weaken the interlayer magnetic coupling between the Mn spins. A significant magnetoresistance as large as 3.5% was observed at room temperature in magnetic fields below 10 kOe. The metamagnetic transition seems to give rise to the magnetoresistance via s–d scattering.