Magnetic anisotropy strength and surface alloy formation in Mn/Co/Cu(001) overlayers

Abstract

The correlation between the structure and magnetic properties of ultrathin Mn overlayers grown on fcc Co/Cu͑001͒ was studied using low-energy electron diffraction and the magneto-optic Kerr effect in situ. A two-dimensional magnetic c͑2ϫ2͒ Mn-Co͑001͒ surface alloy was found to be stabilized in the range 0.3-0.8 ML Mn overlayer thickness. Within this thickness range Mn is ferromagnetically coupled to the fcc Co͑001͒ underlayer. Above one monolayer of Mn, the c͑2ϫ2͒ surface reconstruction fully disappears and the Mn overlayers are no longer ferromagnetically ordered. Furthermore, it is shown that the Kerr signal, magnetic anisotropy strength, and coercivity are correlated with the stabilization of the MnCo surface alloy and growth conditions. ͓S0163-1829͑99͒02709-5͔

Layered antiferromagnetic spin structures of expanded face-centered-tetragonal Mn(001) as an origin of exchange bias coupling to the magnetic Co layer

“…22,23 The STM images point out the smooth surface morphology of Mn films with respect to the two layers exposed to the top of the surface and give an indication of the two-dimensional layer-by-layer growth mode of Mn epitaxial films, also supporting the consistency reported previously. [22][23][24] For the vertical-interlayer-distance expansion of the e-fct-Mn films, a c/a ratio of ∼1.045 as the thickness of covered Mn layers of up to 3.5 mL has been confirmed and determined by either x-ray photoelectron-diffraction or LEED-I/V measurements. 8,9 After we have realized the growth and crystalline structures of Mn films on Co/Cu(001), the SP-STM experiments at 77. of the Mn surface layers rather than the proposed c(2 × 2) antiferromagnetic compensated-spin structures in the previous study.…”

Absolute Band Mapping by Combined Angle-Dependent Very-Low-Energy Electron Diffraction and Photoemission: Application to Cu

“…10 On fcc Co͑100͒, Mn has been found to grow as p(1ϫ1) overlayer; 11 however, weak c(2ϫ2) low-energy electron diffraction ͑LEED͒ spots have recently been reported for 0.3-0.8 ML coverage and considered as indication for surface alloy formation. 12 On Fe͑100͒ and Fe͑110͒, on the other hand, only p(1ϫ1) Mn superstructures have been observed and interpreted as layer growth without interdiffusion. 13,14 Interestingly, a weak c(2ϫ2) superstructure has also been found for 1 ML Co/Cu͑100͒ after annealing.…”

Mn 3d majority spin states in c (2 × 2) Mn/fcc-X(001) systems (X = Fe, Co, Ni, Cu)

“…A similar c(2 × 2) superstructure in the low energy electron diffraction (LEED) pattern has also be observed for Mn deposited on the (001)-face of pseudomorphic grown fcc-Co/Cu(001) films [8] and the same structure as for Mn/Cu(001) and Mn/Ni(001) was concluded. The Mn atoms couple ferromagnetically to Ni and Co in the c(2 × 2) MnNi and MnCo surface compounds, respectively, as proved by measurements of circular dichroism [9,10] and magneto-optical Kerr effect [11]. For c(2 × 2) MnCu/Cu(001) manganese atoms are in a high spin ground state [12,9] and evidence for a long-range order below 50 K was found [13].…”