Vortex induced by impurity

Magnetic Vortex Induced by Nonmagnetic Impurity in Frustrated Magnets
Shi-Zeng Lin, Satoru Hayami, and Cristian D. Batista
Phys. Rev. Lett. 116, 187202 (2016)

Vortex solutions for $H_{\mathrm{sat}}<H<H_{\mathrm{sat}}^I$obtained from numerical simulations of $H$ in the classical limit ($S\to \infty$). (a) Vortex bound to a single-site nonmagnetic impurity for different field values. The vortex helicity is arbitrary due to the U(1) symmetry of $H$. (b) Giant vortex solution ($l=\pm 2$) obtained after removing the spins from the six sites indicated with black dots, for $J_3=-0.2777J_1$ and $Q=2\pi /12$. The saturation field is $H_{\mathrm{sat}}=0.02235\left|J_1\right|$ and $H_{\mathrm{sat}}^I=0.04725\left|J_1\right|$.