Proximity-induced magnetic moments in Pt by Co and Gd in [Co/Gd/Pt]_nmultilayers

The proximity effect, which describes the tendency for a heavy metal (HM) to develop a magnetic moment near an interface with a magnetic material, has attracted interest recently due to its relevance to spintronics. Thus far more attention has been paid to proximity effects at HM/3d transition metal interfaces, and HM/rare earth structures have been largely overlooked. Here we use element specific x-ray magnetic circular dichroism (XMCD) and first-principles density-functional theory (DFT) to study the proximity-induced Pt moment in  [Co(0.5)/Gd(1)/Pt(1)]_n=10(nm) multilayers. XMCD measurements show that the temperature dependence of the induced Pt moment follows the trend of the magnitude of Co magnetization (|M_Co|) from 300 K to 50 K, but follows that of Gd (|M_Gd|) from 50 to 5 K. DFT calculations reveal that there are induced Pt moments at both the Pt/Co and the Pt/Gd interfaces with the directions parallel (antiparallel) to that of the Co (Gd). Moreover, the Pt moment at the Pt/Gd interface is induced dominantly by the neighboring Gd layer. Our results demonstrate that a magnetic moment can be induced in Pt not only by a 3d transition metal but also by a rare earth element, which is an important consideration for heterostructure spintronic systems.