Europhys. Lett., 63 (5) , pp. 771-777 (2003)
Overdamped interlayer exchange coupling and disorder-dominated magnetoresistance in superlatticesP. Padhan1, R. C. Budhani1 and R. P. S. M. Lobo2
1 Department of Physics, Indian Institute of Technology - Kanpur, 208016, India
2 Laboratoire de Physique du Solide, Ecole Supérieure de Physique, Chimie Industrielles de la Ville de Paris, CNRS UPR 5 - 75231 Paris, Cedex 5, France
(Received 14 January 2003; accepted in final form 20 June 2003)
Magnetization and magnetoresistance (MR) measurements are reported on superlattices consisting of alternate layers of 20 unit cell (u.c.) thick ( ) and n u.c. ( ), where n varies from 1 to 10. The saturation field ( ) and remnant magnetization ( ) show antiferromagnetic (AF) interlayer coupling for followed by an overdamped oscillatory behavior with a period of with the increasing n. The low-temperature MR of the AF-coupled superlattices is characterized by a steep increase up to a critical field ( ) followed by a ( ) dependence, whereas in the ferromagnetically coupled samples the MR rises monotonically as with no . We attribute the overdamped oscillations in and , and the dual nature of MR to disorder modified quantum interference in the spacer layers.
75.70.Cn - Magnetic properties of interfaces (multilayers, superlattices, heterostructures).
75.47.Gk - Colossal magnetoresistance.
75.47.Lx - Manganites.
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