tection are λF Y ≈ 100 nm and λT EY ≈ 3 nm. In the
current experiment, the Mn XMCD measured using FY
and TEY are thus sensitive to the bulk of the (Ga,Mn)As
ﬁlm and the near-interface layers, respectively.
Figure 2(a)-(c) shows the magnetic ﬁeld dependence of
XMCD asymmetry, deﬁned as ( Il − Ir)/ (Il + Ir) where
Il(r) is the absorption for left- (right-) circularly polarized
x-rays. This is measured at the Fe and Mn L3 absorption
peaks for a Fe(2 nm)/(Ga,Mn)As(10 nm) sample at 2 K.
The external ﬁeld is applied along the photon incidence
direction, which is at 70◦ to the surface normal with
an in-plane projection along the [110] axis. The XMCD
data show that the Fe ﬁlm displays a square hysteresis
loop with a single magnetization switch, as expected for
a monocrystalline Fe ﬁlm with strong uniaxial magnetic
anisotropy. The Mn XMCD shows a more complicated
loop due to the eﬀect of the interlayer coupling. The pro-
jected Mn moment aligns antiparallel to the Fe moment
at remanence, and undergoes a magnetization reversal of
opposite sign to the Fe. With further increase of the ex-
ternal magnetic ﬁeld, the Mn moment gradually rotates
away from antiparallel alignment with the Fe layer, and
into the ﬁeld direction. Qualitatively similar behavior
is observed for the Fe(2 nm)/(Ga,Mn)As(20 nm) sam-
ple: the (Ga,Mn)As layer is aligned antiparallel to the
Fe layer at zero ﬁeld, although the bias ﬁeld is lower by
approximately a factor of two.
Clear diﬀerences are observed between the Mn XMCD
hysteresis loops obtained using TEY and FY detection
modes. For FY the magnitude of the XMCD is similar
(but of opposite sign) at remanence and at high mag-
netic ﬁelds, whereas for TEY at remanence it is approx-
imately a factor of two larger than at 1000 Oe. The
MnL2,3 XMCD spectra recorded at remanence and at
1000 Oe, shown in Fig. 3, conﬁrm this result. At re-
manence the FY and TEY detected XMCD have similar
magnitudes. However, under a large external ﬁeld the
XMCD is substantially smaller in TEY than in FY, con-
ﬁrming that the net magnetization of the Mn ions near
the interface is signiﬁcantly less than in the bulk of the
(Ga,Mn)As ﬁlm. This is the case even up to the high-
est ﬁeld applied (20 kOe). By applying the XMCD sum
rules14 to the TEY data, and by comparing the spectra to
previous measurements on well-characterized (Ga,Mn)As