Magnetic properties and atomic structure of La_(2/3)Ca_(1/3)MnO_(3)-YBa_(2)Cu_(3)O_(7) heterointerfaces

摘要

A heterostructure comprised of a 2.7 nm (7 unit cell) thick layer of the metallic ferromagnet La_(2/3)Ca_(1/3)MnO_(3) and two 50 nm thick layers of the high-temperature superconductor YBa_(2)Cu_(3)O_(7) epitaxially grown on (100) SrTiO_(3) 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 La_(2/3)Ca_(1/3)MnO_(3). A massive reduction in the magnetization previously inferred from sputter-deposited La_(2/3)Ca_(1/3)MnO_(3)-YBa_(2)Cu_(3)O_(7) 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-CuO_(2)- and -BaO-MnO- at the top and bottom interface.