Direct Observation of Surface Alloying and Interface Roughening: Growth of Au on Fe(001)

Abstract

Scanning tunneling microscopy studies on the growth of Au on Fe(001) are reported. A surface alloy is observed for submonolayer deposition ( <0.5 monolayer) at temperatures higher than 370 K. This surface-confined alloy demixes when it is covered with Au and in combination with imperfect layer-by-layer growth a rough interface consisting of Au islands in and Fe islands on the original Fe(001) substrate is created. A real-space high resolution study of this buried interface is possible because of the large difference in interlayer spacing between bcc Fe(001) and fcc Au(001).

Embedded Co nanostructures on Au(001) substrate studied by scanning tunneling microscopy

“…Since magnetic properties are very sensitive to the Co/Au interface, detailed information on nanostructures of surfaces and interfaces with respect to the morphology is essential for understanding the structural and magnetic properties of bcc Co. Imaging of buried islands in metallic substrates is a generally delicate task by STM, but it is demonstrated here to be practical by virtue of the large difference in interlayer spacing of two metals [10] and the presence of the Shockley surface band [11]. We demonstrate here that the number of Co and Au layers with respect to the buried Co islands can be determined with enough accuracy from the observed height difference by STM.…”

Thin-film nanostructures: Substructural aspects

“…Au growth on (001) Fe at T s > 370 K is characterized by surface alloying at Θ = 0.5. At larger layer thicknesses, Bischoff et al [81] observed phase segregation and surface roughening due to the formation of Au monoislands and Fe islands on the parent surface. Murray et al [82] discussed interlayer mixing in Pd/Cu(110) and Pd/Ag(110) systems.…”

Interfacial mixing in heteroepitaxial growth

“…Often the rate for the reverse process is so small that it can be neglected. Such a behavior occurs, e.g., for Cr on Fe [8], AlAs on GaAs [9], Nb on Fe [10], and Au on Fe [11].…”