Magnetic effects in an itinerant electron antiferromagnetic Cr+1.72 at. % Fe alloy single crystal

Measurements of the temperature and pressure dependences of the longitudinal-mode ultrasonic wave velocities (ν_L) as well as the temperature dependence of the electrical resistivity (ρ) of a Cr1-c Fec alloy single crystal with c=0.0172 are reported. The ν_L -T curve displays two prominent anomalies of magnetic origin. One is a deep minimum at the Náel temperature (TN =274 K) and the other a sharp change in slope at a lower temperature Tt =243 K. The anomaly at Tt is absent on the ρ -T curve, but the Náel transition is accompanied by a very prominent continuous rise in ρ on cooling through TN. The observations at Tt cannot be directly explained in light of the present magnetic phase diagram of the Cr-Fe system. There is a large contribution of about 50% from magnetic effects to the residual resistivity of Cr+1.72 at. % Fe at 0 K. This contribution is ascribed to spin-density-wave and local impurity effects.