A helium atom scattering study of the growth of platinum on nickel(100)

The growth of thin platinum films on a nickel (100) substrate is investigated by helium atom scattering. Growth is shown to be disordered for all temperatures between 150 and 600 K, resulting in continual surface roughening and an absence of atomically flat terraces. We separate growth into three main regimes. First, at temperatures below 250 K, growth is three-dimensional and is described using a 'hit and stick' regime of limited adatom mobility. Between 250 and 370 K, deposited films remain three-dimensionally rough but involve intermixing of Pt and Ni. At temperatures above 370 K, large three-dimensional structures are absent and alloying is extensive, occurring via a sequence of thermally activated and well-defined alloy phases. Complete alloying occurs above 650 K.