Ag-induced spin-reorientation transition of Co ultrathin films on Pt(111)

Abstract

The surface magneto-optical Kerr effect was used to study the magnetic properties of Co ultrathin films deposited on Pt͑111͒. The easy axis of the magnetization changes from the out-of-plane to the in-plane direction after the coverage of Co is larger than 3.5 ML. The spin can reorient to the normal of the surface when the proper thickness of Ag overlayers is deposited on Co/Pt͑111͒ with the in-plane magnetization. The out-of-plane magnetization and its coercivity as a function of Ag coverage were investigated during the spin-reorientation transition. The easy axis of the magnetization can shift back to the in-plane direction after the Ag overlayers are sputtered out. The chemical compositions of the interfaces were measured by Auger electron spectroscopy. The mechanism of the spin-reorientation transition induced by Ag is discussed.

Finding stabilized coercivity in a study of thickness and temperature dependent Co/Ag/Ge(001) ultrathin films

“…[6]. Only the surface anisotropy constant K S Co-Ag is positive, while the other terms are all negative [27,28]. Hence, when the thickness of Co layers d Co is reduced, surface anisotropy in the Co-Ag interface becomes the main factor in comparison with the intrinsic magnetocrystalline anisotropy and the other interface anisotropy.…”

Structure and magnetic properties of ultrathin Ni films on Pt(111) with Co buffer layers

“…The easy axis of the magnetization for 1 ML Co/ Pt͑111͒ is out of plane, the same as that of our previous study. 18 Therefore only the polar Kerr hysteresis loop was observed for d Ni = 0 ML. We were surprised that only the polar Kerr signals were observed when d Ni ഛ 24 ML.…”

“…The magnetic anisotropy energy can be used to describe the tendency of the alignment of the magnetization. 18 The magnetic anisotropy energy density can be written as E = K ef f sin 2 ⌰ if we neglect the high-order terms. The easy axis of the magnetization prefers the out-ofplane direction when K ef f Ͼ 0.…”

“…On the other hand, the easy axis of the magnetization prefers the in-plane direction when K ef f Ͻ 0. The effective magnetic anisotropy K ef f of the Ni/ Pt͑111͒ can be written as 18,19 …”

Enhancement of magneto-optical Kerr effect for Co ultra-thin film on Pt(111) with Ag buffer layer

“…All the ultra-thin films were deposited at room temperature. The detail processes of the sample preparation and the equipment in UHV have been described elsewhere [5].…”