Magnetic properties and atomic structure of La2/3Ca1/3MnO3–YBa2Cu3O7 heterointerfaces

A heterostructure comprised of a 2.7 nm (7 unit cell) thick layer of the metallic ferromagnet La2/3Ca1/3MnO3 and two 50 nm thick layers of the high-temperature superconductor YBa2Cu3O7 epitaxially grown on (100) SrTiO3 by pulsed-laser deposition was characterized by magnetization measurements and spherical-aberration-corrected high-resolution transmission electron microscopy (HRTEM). The saturation magnetization is about half of that in bulk La2/3Ca1/3MnO3. A massive reduction in the magnetization previously inferred from sputter-deposited La2/3Ca1/3MnO3–YBa2Cu3O7 heterostructures can be ruled out. HRTEM image analysis, combined with image simulation and a focus series reconstruction, revealed atomically sharp epitaxial structures with stacking sequences –(La,Ca)O–CuO2– and –BaO–MnO– at the top and bottom interface.