IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+TF-ThA

Paper MI+TF-ThA4
The Magnetic Properties of Fe@sub 50@Mn@sub 50@/Cu Multilayers

Thursday, November 1, 2001, 3:00 pm, Room 110

Session: Magnetic Thin Films and Surfaces I
Presenter: G.J. Mankey, University of Alabama
Authors: G.J. Mankey, University of Alabama
S. Maat, University of Alabama
L. Shen, University of Alabama
S.C. Byeon, University of Alabama
E. Ada, University of Alabama
J.L. Robertson, Oak Ridge National Laboratory
M.L. Crow, Oak Ridge National Laboratory
T.C. Schulthess, Oak Ridge National Laboratory
W.H. Butler, Oak Ridge National Laboratory
Correspondent: Click to Email
The temperature dependent magnetic properties of 50-period multilayers of Fe@sub 50@Mn@sub 50@/ Cu were investigated by squid magnetometry and neutron scattering. Squid magnetometry of a polycrystalline multilayer revealed that field cooling of the multilayer from above the Néel temperature aligns the uncompensated spins, resulting in ferromagnetic ordering of a small fraction of the sample. This ferromagnetic ordering may contribute to the exchange-bias effect observed in Fe@sub 50@Mn@sub 50@/ferromagnet layers. For neutron diffraction measurements, epitaxial multilayers with a fcc (111) surface orientation were produced by magnetron sputtering on H-terminated Si(110). The neutron diffraction measurements reveal a wider mosaic spread in the magnetic lattice relative to the chemical lattice and that only a portion of the Fe@sub 50@Mn@sub 50@ alloy was antiferromagnetically ordered. These observations suggest the domain walls occupy a significant fraction of the Fe@sub 50@Mn@sub 50@ volume. The critical behavior of the antiferromagnetic ordering was determined by measuring the temperature dependence of the magnetic diffraction peak with neutron diffraction. For the first heating cycle, a Néel temperature of 510K and critical exponent of 0.357 are found, consistent with bulk 3D Heisenberg behavior. However, measurements during subsequent heating cycles showed that annealing to 480 K irreversibly changes the microstructure of the multilayer, resulting in a reduction in the magnetization, a reduction of the critical exponent, and an increase of the Néel temperature. XPS depth profiling of the multilayer before and after annealing shows that the interface widths increase due to intermixing of the Fe@sub 50@Mn@sub 50@ and Cu layers. The intermixing is the cause of the changes in magnetic properties. Sponsored by ARO DAAH-04-96-1-0316, NSF MRSEC DMR-9809423, and DOE DMR DE-AC05-96OR22464.