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 studi ed via scanning-tunneling microscopy (STM). Irregularly shaped islands are observed. The images show features with nontopographic contrast. Both obser vations are interpreted as evidence for interface exchange processes betwee n 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 circ ular dichroism measurements, we show that intermixing is not the reason for the recently reported reduced magnetic moments of 4-5 ML Ni/Cu(001).