Understanding quantum materials using strain-sensitive x-ray diffraction imaging*

Understanding the local crystalline strain around point defects, such as the nitrogen vacancy center in diamond and divacancy complexes in SiC, is a critical step toward improving spin coherence and optical properties. These lattice perturbations affect both the charge and the optical transition frequency stability of the defect, limiting their use as nanoscale sensors and quantum bits for quantum communication applications. While local strain can be mitigated using applied electric fields and external static strain, direct observation of inhomogeneous strain fields around these defects at the nanometer length scale remains challenging. Here we present work on the development of synchrotron-based, strain-sensitive x-ray imaging techniques which we use to map the local lattice perturbations within diamond and SiC crystals. These tools can help understand the interaction of defects with dynamically driven strain fields as well as probe the defect creation process to help improve the basic properties of quantum materials. We show two separate techniques: strain-sensitive Bragg coherent diffraction imaging (BCDI) that can measure the three-dimensional lattice strain of individual diamond and SiC nanoparticles as a function of annealing temperature [1,2], and a stroboscopic scanning x-ray diffraction microscopy (s-SXDM) imaging approach that can spatially map acoustic waves in SiC [3] and probe the local strain around crystalline defects. Combining these techniques with growth and implantation protocols could provide a direct means to understand the local crystalline environment surrounding point defect as well as a pathway towards improving their spin properties.

[1] S.O. Hruszkewycz, et al., APL Materials 5, 026105 (2017).
[2] S.O. Hruszkewycz, et al., Phys. Rev. Materials 2 (8), 086001 (2018).
[3] S. J. Whiteley, et al., arXiv:1808.04920

In collaboration with S. J. Whiteley, S. O. Hruszkewycz, M. V. Holt, & D. D. Awschalom.