Enhanced magnetic moment of ultrathin Co films measured by in situ electrodeposition in a SQUID

A special electrochemical cell enabling in situ electrodeposition in a SQUID magnetometer is applied to study the magnetic moment of ultrathin Co films during growth on an Au(111) substrate. The in situ electrodeposition approach allows a total elimination of the magnetic background signal of the substrate, thus the magnetic moment which arises exclusively from the deposited Co film could be measured with monolayer sensitivity. The average thickness of the deposited Co films dav as determined from the transferred charge can be adjusted easily by varying the parameters of the electrodeposition. Hence, the magnetic moment of Co thin films could be determined in absolute terms as a function of the film thickness dav. For the first few atomic layers an enhancement of the magnetic moment per Co atom compared to the bulk could be observed, which increases steadily with lowering dav, reaching up to 40%.