Emergent ferroic orders in SmMnO3:NiO nanocomposites

Abstract

Exploiting self-assembled nanocomposites allows the emergence of new ground states and multifunctionalities within a heterosystem. Particularly, in the form of vertically aligned nanocomposites, densely distributed vertical heterointerfaces enable three-dimensional engineering control, which is efficient and flexible. These three-dimensional nanocomposites provide a vast platform for tuning magnetic and electronic properties in functional perovskite oxides, such as rare earth manganates. Here, we explored a vertically aligned system composed of orthorhombic SmMnO₃ as the matrix and stiff NiO as the embedded phase, both are antiferromagnetic. The atomic structure and unique structural distortion were determined using aberration-corrected transmission electron microscopy. By using piezoelectric force microscopy, the well-defined piezoresponse with 180° phase switching was observed, and macroscopic ferroelectric tests were further performed to demonstrate a polarization of 0.017 μC/cm² at room temperature. Furthermore, clear ferromagnetism signal with a Curie temperature of about 120 K was revealed via well-defined hysteresis loops and temperature-dependent magnetization curves, suggesting the effectiveness of integrating antiferromagnetic building blocks to induce magnetic interaction. The present work provides a feasible pathway to engineer potential multiferroic by combining lattice rotation and vertical-interface-mediated magnetic coupling approach.