Verlag des Forschungszentrums Jülich
JUEL-3455 Magnetic properties of ultrathin films were studied by magnetic circular dichroism in
x- ray absorption (MCXD) and spin and angle resolved photoelectron spectroscopy (SARPES).
The magnetization of Mn submonolayers on Fe(100) and Ni(100) was analyzed as a function of
coverage and temperature. The Mn moment couples parallel to Ni and antiparallel to Fe. For
0.02 ML Mn/Fe the Mn is in a high spin state. With increasing Mn coverage the average Mn
moment decreases in accordance with the tendency of Mn to antiferromagnetism. The
magnetization of the c(2x2) NiMn surface alloy on Ni/Cu(100) reveals that near the
critical temperature the magnetization in the surface region decreases faster than the
average magnetization of the whole Ni film, because at the surface the reduced
coordination number leads to enhanced spin fluctuations. The corresponding empirical
critical exponent beta describing the magnetic phase transition is slightly enhanced at
the surface. The magnetic 3d moments of ultrathin fcc Fe overlayers deposited at T=300K on Cu(100)
and Co(100) were determined at T=110K for the first time. For 1-4 ML Fe the Fe is in a
high spin state with a spin moment of 3.0 [my]B magnetons on Co and 2.8 [my]B
magnetons on Cu. For 5-10 ML the average Fe spin moment is 1.1 [my]B magnetons
on Co and 0.8 [my]B magnetons on Cu, i.e., on both substrates the surface
region and on Co additionally the Fe layer at the Fe-Co interface is ferromagnetically
ordered. Indications for layerwise antiferromagnetism in the interior of the Fe films were
not observed. In addition, magnetic circular dichroism in x-ray emission (SXE) was studied with
improved energy resolution. For excitation 1.5 eV above the Fe L3 absorption
threshold the asymmetry is only 3% at the maximum of the L3 emission and the
shape of the spectra is dominated by the density of states of the minority electrons
because in the absorption step there are 11 times more minority than majority states
available. The SXE spectra contain information about the spin resolved occupied density of
states.
Schmitz, Detlef
Magnetic properties of ultrathin films studied by circular dichroism in x-ray spectroscopies
129 S., 1997
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