Direct imaging of stress field around a dislocation in diamond

Dislocations are fundamental crystal defects whose stress fields govern a wide range of material properties. The analytical form of the stress tensor around a dislocation was established by elasticity theory more than 80 years ago and has provided a theoretical basis for evaluating essential characteristics of dislocations. However, direct experimental verification has long remained out of reach because it has been difficult to measure the components of the stress tensor with conventional methods. Here, we present the experimental visualization of four components of the stress tensor around a dislocation in diamond. Using quantum sensors based on nitrogen-vacancy centers, we mapped the shear components (σxy, σyz, and σzx) together with the trace of the stress tensor (σxx + σyy + σzz) around a region where the stress field was considered to be dominated by a single 45° dislocation. The observation showed that the variations of stress in σxx + σyy + σzz, σxy, σyz, and σzx were approximately ±0.03, ±0.01, ±0.01, and ±0.01 GPa, respectively, and the distribution of stress exhibited a point-symmetric shape centered around the dislocation. This experimental result exhibited good agreement with the theoretical framework, thus providing experimental validation of four components of the stress tensor around the dislocation derived from the elastic theory.