Atomic exchange processes at the interface and their role on the magnetic moments of ultrathin Ni/Cu(001) films

To investigate the interface of Ni/Cu(001) coverages up to 1.1 monolayers (ML) are deposited at room temperature on a Cu(001) single crystal and studied via scanning-tunneling microscopy (STM). Irregularly shaped islands are observed. The images show features with nontopographic contrast. Both observations are interpreted as evidence for interface exchange processes between Cu and Ni atoms. The tip influence in the imaging of the intermixed areas is demonstrated. By combining the STM information with x-ray magnetic circular dichroism measurements, we show that intermixing is not the reason for the recently reported reduced magnetic moments of 4--5 ML Ni/Cu(001).