  The magnetic proximity effect in top and bottom Pt layers induced by Co in
Ta/Pt/Co/Pt multilayers has been studied by interface sensitive, element
specific x-ray resonant magnetic reflectivity. The asymmetry ratio for
circularly polarized x-rays of left and right helicity has been measured at the
Pt $L_3$ absorption edge (11567 eV) with an in-plane magnetic field ($\pm158$
mT) to verify its magnetic origin. The proximity-induced magnetic moment in the
bottom Pt layer decreases with the thickness of the Ta buffer layer. Grazing
incidence x-ray diffraction has been carried out to show that the Ta buffer
layer induces the growth of Pt(011) rather than Pt(111) which in turn reduces
the induced moment. A detailed density functional theory study shows that an
adjacent Co layer induces more magnetic moment in Pt(111) than in Pt(011). The
manipulation of the magnetism in Pt by the insertion of a Ta buffer layer
provides a new way of controlling the magnetic proximity effect which is of
huge importance in spin-transport experiments across similar kind of
interfaces.
