Neutron scattering studies of magnetic semiconductor thin films and superlattices. T. M. Giebultowicz 1 and Henryk Kępa 2,1 1. Dept. of Physics, Oregon State university, Corvallis, OR,USA 2. Institute of Experimental Physics, Warsaw University, Poland Subtitle:
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T. M. Giebultowicz1and Henryk Kępa2,1
1. Dept. of Physics, Oregon State university, Corvallis, OR,USA
2. Institute of Experimental Physics, Warsaw University, Poland
Doing neutron scattering in Oregon?
When we started our research long time ago, we had no other choice
than to study
Antiferromagnetic / NonmagneticSuperlattices (e.g., EuTe/PbTe)
bulk TN = 9.6 K
EuTe 3-m epilayer
NIST Center for Neutron Research NG1reflectometer
= 4.75 Ǻ
Curie temperatures for
strongly p-type alloys
with 5% Mn.
Year 2000: We find Dr. A. Sipatov from
Ukraine, who grows very interesting
EuS/PbS and EuS/YbSe superlattices!
EuS – Heisenberg ferromagnet TC = 16.6 K (bulk), Eg=1.5 eV
PbS – narrow-gap (Eg=0.3 eV) semiconductor (n≈ 1017 cm-3)
YbSe – wide-gap (Eg=1.6 eV) semiconductor (semiinsulator)
all NaCl-type structure with lattice constants:
(lattice mismatch ≈ 0.5%)
number of repetitions
the EuS/PbS system
(NG-1 reflectometer, NIST Center for Neutron Research)
J.Blinowski & P.Kacman, Phys. Rev. B 64 (2001) 045302.
P.Sankowski & P.Kacman, Acta Phys. Polon. A 103 (2003) 621
Advantages of using polarized neutrons… electrons
FM domains in Ga(Mn)As/GaAs superlattices
Here are data from a Ga(Mn)As/GaAs superlattice
(6% of Mn) obtained using an unpolarized beam:
Atomic spins S and the applied magnetic
field H lie in the x-z reflecting planes.
External field H and the neutron
polarization P are parallel to z-axis
Parallel to H projections of S non-spin-flip (NSF) scattering
Perpendicular ones purely magnetic spin-flip (SF)
EuS/YbSe (46/20) Å.
in-plane  axis horizontal
EuS/PbS (30/4) Å - polarization analysis of the 1-st AFM SL Bragg peak
Polarized neutrons and the in-plane magnetic anisotropy in EuS/PbS & EuS/YbSe
Polarized neutron reflectivity studies
The model EuS/PbS & EuS/YbSe
…. etc., where:
is the angle of rotation of the sample about Q
Neutron polarization analysis sample about Q
For saturated sample about Qsampleα=90º