CERIUM MOMENT COLLAPSE IN TERNARY SILICIDES CEPD2-XMNXSI2 (0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-2)

Cerium L3 XANES (x-ray-absorption near-edge-structure) spectra were analyzed to separate Ce moment contributions and mixed valence (MV) in complex magnetic silicides CePd2-xMnxSi2 (0 less-than-or-equal-to x less-than-or-equal-to 2). The Ce valence mixing does not vary linearly with x, but increases rapidly for x greater-than-or-equal-to 1.5. The associated moment collapse correlates with pronounced deviations of the unit-cell volume from Vegard law and the onset of structural instability. Reorientation of [001] Mn 3d antiferromagnetic order for x < 2 appears to rapidly suppress the weak Ce valence mixing coexisting with antiferromagnetic order in CeMn2Si2.