Magnetism and transport properties of metamagnetic Mn1-xCrxAu2

Crystallographic, magnetic and electric properties of metamagnetic Mn1-xCrx Au2 were studied. Pure MnAu2 has a helical-spin structure and the structure changes to a ferromagnetic state below the Neel temperature T-N (similar t o 360 K) and above a threshold magnetic field H-th (similar to 10 kOe at 30 0 K). The T-N, H-th 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 th e interlayer magnetic coupling between the Mn spins. A significant magnetor esistance as large as 3.5% was observed at room temperature in magnetic fie lds below 10 kOe. The metamagnetic transition seems to give rise to the mag netoresistance via s-d scattering. (C) 1999 Elsevier Science S.A. All right s reserved.