PRESSURE INDUCED NON-COLLINEAR MAGNETIC STRUCTURES IN Fe-RICH INTERMETALLICS.

The results of a complementary study of magnetic properties, magnetovolume effects and neutron diffraction studies under pressure in R 2 Fe 17 compounds with non-magnetic R (R - Y, Ce, Lu) are presented. The collinear ferromagnetic phase existing at low temperature in all three compounds is suppressed at high pressures. The critical pressure P C depends on the compound studied ( P C  ≅ 2.5 kbar for Ce 2 Fe 17 , P C  ≅ 3.5 kbar for Lu 2 Fe 17 , P C  ≅ 12 kbar for Y 2 Fe 17 ). Incommensurate non-collinear magnetic structures that replace the ferromagnetic ones under high pressures have similar features - magnetic moments in each layer of atoms (perpendicular to z -axis) are parallel each other, their direction helically changes from layer to layer. A generalised phase diagram of the studied R 2 Fe 17 compounds was determined with use of the recent compressibility data. [ABSTRACT FROM AUTHOR]