Table2-X-ray absorption fine structure (XAFS) data for Fe84Ni16
We investigated the magnetism of body centered cubic (bcc) FeNi alloys (Fe92Ni08, Fe87Ni13, and Fe84Ni16) as a function of pressure at room temperature through the bcc to hexagonal closed packed (hcp) phase transition. In each case, the fully saturated magnetic remanence attained maxima at the hysteretic bcc-hcp and hcp-bcc transition boundaries upon compression and decompression. Magnetization maxima generally shifted to lower pressures with increasing Ni concentration. In Fe84Ni16, X-ray magnetic circular dichroism (XMCD) at the K-edge of Fe measured in a 2.5 T field together with X-ray absorption spectroscopy indicate that the magnetism defined by XMCD divided by the proportion of bcc attains a maximum in the transition regions, similar to the magnetic remanence measurements. The data imply that interaction stresses due to a lattice mismatch between bcc and hcp Fe phases, together with defect-riddled martensite, carry an enhanced magnetic remanence that can persist into the pressure range where only pure hcp Fe was considered stable.