Magnetic and transport characteristics of long-period [(LaMnO3)n/(SrMnO3)n]m (n ≥ 3) superlattices.

Artificial long-period superlattices of antiferromagnetic LaMnO3 and SrMnO3 ([(LaMnO3)n/(SrMnO3)n]m with n ≥ 3) were deposited on SrTiO3 (001) substrates by pulsed laser depositon monitored in situ by reflective high-energy electron diffraction. X-ray diffraction and atomic force microscopy studies reveal the sharp interfaces and smooth surface in the superlattices. Magnetic and transport characteristics are observed to depend strongly on the period of the superlattice. An interfacial ferromagnetic phase is found to coexist with the two antiferromagnetic components. The observed ferromagnetic magnetization is ascribed to Mn3+-O-Mn4+ double exchange across the LaMnO3/SrMnO3 interface. The spin-glass-like behaviors, the large magnetoresistance, and the evolution of the transport mechanism with increasing period in the superlattices are discussed in terms of spin frustration due to the competition between the ferromagnetic and antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]