Cs. Arnold et al., Magneto-optic Kerr effect study of a two-step reorientation transition of an ultrathin magnetic film, J APPL PHYS, 87(9), 2000, pp. 5478-5480
The magnetic reorientation transition for ultrathin Fe films on Gd is studi
ed. At low temperatures, the films are magnetized in plane and at intermedi
ate temperatures they undergo a reorientation to out of plane. The reorient
ation is attributed to the reducing magnetization of Gd as it approaches it
s Curie temperature and the perpendicular magnetic anisotropy at the Fe sur
face. Detailed measurements of the reorientation were made in situ using th
e magneto-optic Kerr effect (MOKE). The first step, at low temperature, is
a continuous, reversible reorientation of the surface moment from in plane
to canted out of plane; a corresponding peak in the susceptibility identifi
es it as a second-order phase transition. The second step is a discontinuou
s, irreversible rotation from this canted direction to perpendicular to the
film plane; thermal hysteresis of the magnetization identifies it as a fir
st-order phase transition. The MOKE thermal hysteresis loop shows that the
Gd surface region participates in the first-order phase transition. (C) 200
0 American Institute of Physics. [S0021-8979(00)31508-0].