Hedgehog spin-vortex crystal stabilized in a hole-doped iron-based superconductor. - Meier, William R.; Ding, Qing-Ping; Kreyssig, Andreas; Bud'ko, Sergey L.; Sapkota, Aashish; Kothapalli, Karunakar; Borisov, Vladislav; Valentí, Roser; Batista, Cristian D.; Orth, Peter P.; Fernandes, Rafael M.; Goldman, Alan I.; et al. (NPJ Quantum Materials, 2018)