Structural effects on the magnetic behavior of ultrathin Co films on Cu(001) at the TC jump

The magnetic ordering in ultrathin Co films on Cu(001) has been investigated via the polarization of light emitted after capture of spin-polarized electrons into excited atomic terms during grazing He scattering. A strong increase in the Curie temperature and the remanent spin polarization has been observed at a critical Co thickness tCocr∼1.7ML. In agreement with a recent study on the same heteroepitaxial system, this behavior is attributed to the percolation of Co islands. For growth at an elevated temperature of 410K, hysteresis loops reveal a strong increase in the irreversibility field at which the loop closes. This behavior is explained by an inhomogeneous distribution of growth-induced local magnetic anisotropies which make a complete reversal of the magnetization more difficult