Thermal expansion and ultrasonic velocity and attenuation at the continuous Neel transition in Cr+0.2 at.% V

The thermal expansion of a high quality Cr+0.2 at.% V single crystal shows a well defined continuous Neel transition in contrast with the weak first-order transition in Cr. The change in the nature of the ultrasonic velocity and attenuation anomalies at the phase transition also supports the idea that a tricritical point occurs at some concentration less than 0.2 at.% V in Cr.