Temperature-driven Spin Reorientation Research Articles

A circularly polarized X-ray study of the temperature-dependent spin-reorientation transition of thin Co films

Utilizing vector magnetometry by means of X-ray circular dichroism, the temperature-driven spin reorientation from an in-plane to out-of-plane orientation in thin Co films is studied in an epitaxially grown Au/Co/Au trilayer with decreasing temperature. Probing the remanent state by changing the photon helicity provides evidence for a smooth transition and the formation of a metastable magnetic multi-domain state at temperatures below the transition temperature.

Fe spin structure in Tb/Fe multilayers

The Fe spin structure in ultrahigh-vacuum-deposited hcp Tb(t Tb )/bcc Fe(t Fe ) multilayers (t Tb and t Fe are the Tb and Fe layer thicknesses respectively) with perpendicular magnetic anisotropy (PMA) and large coercivity at low temperatures was investigated by 57 Fe Mossbauer spectroscopy, the polar magneto-optical Kerr effect, and superconducting quantum interference device magnetometry. A spontaneous reversible temperature-driven Fe spin reorientation transition from orientation parallel to the film plane to an out-of plane orientation (with Fe spins tilted by an angle relative to the film normal direction) was observed upon cooling below the reorientation temperature T R . At a fixed value of t Tb , T R was found to follow a t -1 Fe behaviour, indicating that the PMA originates from the interfaces. Upon cooling, the perpendicular remanent magnetization shows a step-like increase near the magnetic ordering temperature of Tb, contrary to (T), which exhibits no such anomaly. Apparently, strong coupling of Fe layers via magnetic Tb layers affects the perpendicular magnetic domain structure at remanence. Further, 57 Fe probe layer Mossbauer results concerning structure, composition and Fe spin orientation within Fe-on-Tb and Tb-on-Fe interfaces are reported.

Magnetic susceptibility measurements near the multicritical point of the spin-reorientation transition in ultrathin fcc Fe(111)/2 ML Ni/W(110) films

Iron films grown on a two-monolayer Ni/W(110) substrate undergo a temperature-driven spin reorientation which can be followed experimentally from a low-temperature, perpendicularly magnetized monodomain state all the way to the high-temperature paramagnetic state without a significant change of the atomic structure. Measurements of the magnetic susceptibility, using the magneto-optic Kerr effect, give the entire temperature vs thickness phase diagram for the spin reorientation, including measurements close to the multicritical point where the reorientation and Curie temperatures are equal. The technique is particularly sensitive to the formation of the perpendicularly magnetized domains associated with the spin reorientation and reveals that films with a thickness in the neighborhood of the multicritical behavior also display a maximum in the temperature at which domain formation begins. Thinner films undergo the transition from ferromagnetic-to-paramagnetic behavior directly from the domain state, but no signature of the critical temperature itself is seen in the magnetic susceptibility.