Preparation and properties of EuS films and effects of Fe doping

The preparation techniques and the physical properties, including the structural, magnetic, magnetooptical, optical, and switching properties, of EuS films which are stoichiometric and Fe doped, are examined. Films were deposited onto heated substrates of fused quartz by vacuum evaporation of high-density EuS using an electron-beam gun. X-ray analysis shows polycrystalline structure with bulklike lattice constants. The ferromagnetic T
c
ranges from
\sim18\deg
K for stoichiometric samples to
\sim45\deg
K for Fe-doped films. The optical absorption peak, due to
4f-5d
transitions, occurs at 0.51 μm with a typical absorption coefficient of 1.25 × 10
⁵
/cm at 300°K. The maximum Faraday rotation occurs at 0.58 μm with a specific Faraday rotation of 3.1 × 10
⁵
deg/cm for an incident angle of 65°. The coercive force decreases from 30 Oe at 5.2°K to 20 Oe at 10°K and to zero at
\sim15\deg
K. In EuS films doped with Fe (up to 16 percent by weight) T
c
is increased to
\geq45\deg
K. The optical absorptiou is increased to 2 × 10
⁵
/cm with the absorption peak shifted to 0.55 μm. Another outstanding feature is the square hysteresis loop. At
T < 6\deg
K, the squareness is 0.9, and this extends almost to the Curie point.