WEAK FERROMAGNETIC TRANSITION IN A SINGLE -CRYSTAL LA2CUO4 IN NONSTATIONARY FIELD

The weak ferromagnetic phase transition in an antiferromagnetic single crystal La2CuO4 has been studied in a pulsed magnetic field of 33 ms by measuring the sample conduction. In a rising field the present tran sition has been found to occur in two stages and in the decreasing one a single jump takes place. It Is shown that the treatment of this fac t within the earlier models of magnetic structure of lanthanum cuprate is difficult. Possible refinements of the conventional model have bee n suggested, as well as the mechanisms which can account for the obser ved two-stage transition. The analogy has been drawn with similar beha vior of FeCO3 magnetization in the so-called <<mixed>> state.