Magnetic and morphological properties of ultrathin Fe layers in Zr/Fe/Zr trilayer structures

The structural and magnetic properties of Zr/Fe/Zr trilayer structures, com posed of ultrathin layers of Fe stacked between two pure Zr layers, have be en studied by means of X-ray diffraction (XRD), conversion electron Mossbau er spectroscopy (CEMS) and magnetometry techniques. The XRD results, as wel l as the room temperature saturation magnetization, show a decrease in the amount of bcc-Fe on decreasing the Fz layer thickness. The thickness depend ence of the room temperature coercivity is interpreted as giving evidence f or a switch from a Bloch domain wall structure to a Neel interacting cluste r behaviour, as the Fe layer thickness is decreased below 16 nm. Below this thickness, the temperature dependence of the coercivity as well as the the rmomagnetization behaviour, suggest a magnetic structure composed of crysta lline bcc-Fe interacting clusters. This effect can be related to the appear ance of an amorphous Fe-Zr alloy phase at the grain boundaries which affect s progressively the magnetization process as the magnetic layer thickness i s reduced. (C) 1999 Elsevier Science S.A. All rights reserved.