Seung Sae Hong, Stanford University
Extreme Tensile Strain States in La0.7Ca0.3MnO3 Nanomembranes
Written by Jahlani Odujole
The main goal of Seung Sae Hong’s group was to apply tensile strength in a two-dimensional (2D) membrane and found that atomically-controlled 2D interfaces were highly useful. The researchers were able to get thin films under atomic scale control while maintaining a high degree of freedom. The main focus in this presentation was on complex oxides because these materials present a different kind of magnetism. Nanomembranes can be made from thin-film growth. Pulse laser deposition was applied for epitaxial growth. SrTiO3 was the substrate with Sr3Al2O6 used as a sacrificial layer. The researchers found an unprecedented degree of mechanical freedom. Bulk crystals/ceramics break easily in most cases, which was problem that the researchers were seeking to mitigate. Nanomembranes can achieve very large strain rates. This property can also be used to re-design membranes which allows for continuous control within a material. The 2D materials can be re-stretched and redesigned. This versatile experimental platform can be applied to cryogenic transport and optics storage. Thick membranes were shown to be easily broken, while thin membranes kept stretching without cracking. Normalized x-ray diffraction intensity, with clear phase boundaries, was shown to be a great indicator of deformation behavior. Axial tensile strain can change magnetic phase properties. Density functional theory (DFT) calculations were shown to match well with results.