G. Zangari et al., COERCIVITY AND MICROSTRUCTURE IN CO-PT AND CO-PD THIN-FILMS, Journal of magnetism and magnetic materials, 133(1-3), 1994, pp. 511-515
Thin films of Co-Pt and Co-Pd have been electrodeposited from alkaline
baths based on cobalt amino-citrate complexes and amino-nitrite compl
exes of the noble metal, on copper substrates coated with Ni-P ACD (10
mum). Co-Pd films can be obtained in a wide range of compositions; bo
th fcc and hcp structures can be present (the last one only for Pd les
s-than-or-equal-to 16 at%); the lattice constant varies continously wi
th varying composition. The Bragg diffraction peaks are broadened, sug
gesting a poorly defined crystalline structure or a high density of de
fects. The grains appear to be homogeneous and regular, their size bei
ng generally below 100 nm. Co-Pt films are rich in cobalt; they show a
fcc structure with a lattice constant varying discontinously and with
a (111) PO. A well defined crystalline structure is obtained, with fi
ne and regular crystallites (size below 100 nm), and sharp Bragg peaks
. Differences in microstructure can be related to large differences in
magnetic properties. While Co-Pt films show high coercivities (up to
200 kA/m) and high squareness, Co-Pd films, in the whole range of comp
ositions investigated, show very low coercivities and varying squarene
ss. In the Co-Pd system, hysteresis cycles sometimes suggest the prese
nce of two phases with different micromagnetic behaviours and differen
t coercivities; only one of the phases gives the observed value of coe
rcivity. We further investigated the effect of layering through pulsed
current deposition; the growth of the different phases could be contr
olled through control of deposition parameters in the electrodepositio
n process. Co-Pd films could be promising candidates for thin-film hea
ds in magnetic recording media; their possibilities have not yet been
fully assessed, but their magnetic properties, together with their pos
sible high corrosion resistance and good mechanical properties, deserv
e further studies.