PRESSURE-INDUCED LONG-PERIOD MAGNETIC-STRUCTURE IN LAYERED ANTIFERROMAGNETS RB2MNF4 AND CS2MNF4

The magnetic structure along the axial direction in the layered antiferromagnets, Rb2MnF4 and CS2MnF4, was studied under hydrostatic pressure by using neutron scattering techniques. These compounds revealed predominantly antiferromagnetic stacking of magnetic layers at ambient pressure below their Neel temperatures. Upon applying pressure, however, the stacking changed remarkably; the ferromagnetic stacking became dominant and antiferromagnetic stacking completely vanished. Besides these two dominant peaks, several small peaks, which correspond to longer-period stacking, were also observed. These results are qualitatively explained by taking the competing interplanar interactions into consideration.