Induced ferromagnetism and anisotropy of Pt layers in Fe/Pt(001) multilayers

The structural and magnetic properties of sputter-deposited epitaxial Pt t( Pt)/Fe 7.5 Angstrom (001) multilayers (t(Pt) =0-15 Angstrom) are investigat ed using x-ray diffraction, Kerr magnetometry, and x-ray magnetic circular dichroism (XMCD). X-ray diffraction shows that there is a crystalline phase change from bet to fct at a Pt thickness of approximate to 4 Angstrom. The Fe XMCD is enhanced by approximate to 10% over its bulk value for Pt thick nesses from 1-4 A (bct region), and depressed relative to the bulk by 10-20 % after transition to the fct phase. The Pt layers show a nearly constant m oment up to t(Pt) = 10 Angstrom. XMCD at the N-2.3 edge shows that the Pt m oment has a value of approximate to 0.5 mu(B)/atom. Kerr magnetometry is us ed to determine the in-plane magnetocrystalline anisotropy constant K-1 as a function of t(Pt). It is found that for the Fe thickness studied here, th e easy axis switches from the bct[100] to the bct[110] direction with incre asing t(Pt). This indicates that K-1 has a zero crossing, which occurs at t (Pt)approximate to 1.5 Angstrom. This strong variation in magnetic anisotro py is attributed mainly to the Fe/Pt interface region. However, ferromagnet ic Pt also contributes a significant volume anisotropy which we estimate at -8+/-2 X10(6) erg/cc. [S0163-1829(99)02929-X].