First-principles study of the electronic structure and magnetic properties of3dsingle or multilayers on a Cu(001) substrate:Ni1(orNi4)/Cu(001),Cu2/Ni4/Cu(001),andCo/Cu2/Ni4/Cu(001)

Electronic structures and magnetic properties of ultrathin Ni films $({\mathrm{Ni}}_{n},n=1,4)$ with Cu and Co coverlayers $({\mathrm{Cu}}_{2}/{\mathrm{Ni}}_{4},\mathrm{Co}/{\mathrm{Cu}}_{2}/{\mathrm{Ni}}_{4})$ on the Cu(001) substrate are studied by using the full potential linearized augmented plane wave method with the generalized-gradient approximation for the exchange correlation interactions. The equilibrium structures are determined through their atomic forces. It is found that the spin moments of interfacial Ni atoms are significantly weakened due to the proximity effect from Cu. The Co adlayer in $\mathrm{Co}/{\mathrm{Cu}}_{2}/{\mathrm{Ni}}_{4}/\mathrm{Cu}(001)$ affects the Ni film very slightly due to the screening effects of the Cu layers. The average $3d$ holes increases by about 10% from ${\mathrm{Ni}}_{1}/\mathrm{Cu}(001)$ to ${\mathrm{Ni}}_{4}/\mathrm{Cu}(001).$ In ${\mathrm{Cu}}_{2}/{\mathrm{Ni}}_{4}/\mathrm{Cu}(001),$ the Cu capping layers reduce the average number of $3d$ holes of the Ni atoms by about 7.5% as compared to that in ${\mathrm{Ni}}_{4}/\mathrm{Cu}(001).$ Results are compared to experimental data from recent measurements using magnetic circular dichroism.