Europhys. Lett.
Volume 63, Number 5, September 2003
Page(s) 771 - 777
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 01 November 2003
DOI: 10.1209/epl/i2003-00580-y
Europhys. Lett., 63 (5) , pp. 771-777 (2003)

Overdamped interlayer exchange coupling and disorder-dominated magnetoresistance in $\chem{La_{0.7}Ca_{0.3}MnO_3/LaNiO_3}$ superlattices

P. 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 $\chem{La_{0.7}Ca_{0.3}MnO_3}$ ( $\chem{LCMO}$) and n u.c. $\chem{LaNiO_3}$ ( $\chem{LNO}$), where n varies from 1 to 10. The saturation field ( $H_{\ab{s}}$) and remnant magnetization ( $M_{\ab{r}}$) show antiferromagnetic (AF) interlayer coupling for $n\leq 2$ followed by an overdamped oscillatory behavior with a period of $\approx 4$ $\un{u.c.}$ with the increasing n. The low-temperature MR of the AF-coupled superlattices is characterized by a steep increase up to a critical field ${H_{\ab{s}}}^*$ ( $\approx H_{\ab{s}}$) followed by a $\sim H^\alpha$ ( $\alpha<1.0$) dependence, whereas in the ferromagnetically coupled samples the MR rises monotonically as $\sim H^\alpha$ with no ${H_{\ab{s}}}^*$. We attribute the overdamped oscillations in $M_{\ab{r}}$ and $H_{\ab{s}}$, 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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