Exchange bias effect in epitaxial manganite superlattices

M. E. GÓMEZ; P. PRIETO; G. CAMPILLO; E. BACA; A. HOFFMANN; N. HABERKORN ; J. GUIMPEL

Austin

Congreso; March Meeting; 2003

Epitaxial [La2/3Ca1/3MnO3 / La1/3Ca2/3MnO3]N multilayers were grown in-situ on (001)-SrTiO3 substrates by a high oxygen pressure sputtering process. Superlattices containing N bilayers between 14 and 18 were prepared keeping the thickness of 20 unit cells (uc) for the antiferromagnetic La1/3Ca2/3MnO3 (AF-LCMO) constant and varying the thickness for the ferromagnetic La2/3Ca1/3MnO3 (F-LCMO) in the range from 2 to 20 uc. Below 120 K the field cooling (FC) loops are shifted towards negative fields, evidencing an exchange biasing mechanism in all samples. The temperature dependence of HEB exhibits an exponential decrease with temperature below the blocking temperature for all samples. For ferromagnetic layer thickness t larger than 5 uc, all HEB * t vs. temperature T data fall onto one universal line which indicates that the internal physical processes in the anti-ferromagnetic layers, which are responsible for the exchange bias effect, are the same in all samples and independent from the ferromagnetic layer thickness.