INFLUENCE OF UNIAXIAL TENSION ON ANTIFERR OMAGNETIC TRANSFORMATION INEUROPIUM

An anomalous electrical resistance of Eu near the Neel point was studi ed under a tensile stress (sigma = = 0.25-0.5 kbar) sufficient to decr ease the number of components of the order parameter from 12 to 4. It is found that in the <<fourcomponent>> state the antiferromagnetic tra nsition remains the first order transition in accordance with theoreti cal concepts. Along with the first-order transition domain, there is a wide temperature region where the derivative of resistance is describ ed by a power function of the reduced temperature. In this region the stable value of the critical index lambda = 0.5+/-0.05 found for a non deformed sample can be explained by the influence of the Gaussian tric ritical point. After the sample transition into the <<fourcomponent>> state, the critical index decreases down to lambda = 0.2-0.3.