Roldán-Molina, A., Santander, M.J., Núñez, A.S., Fernández-Rossier, Joaquín
Quantum fluctuations stabilize skyrmion textures
Physical Review B. 2015, 92: 245436. doi:10.1103/PhysRevB.92.245436
URI: http://hdl.handle.net/10045/54255
DOI: 10.1103/PhysRevB.92.245436
ISSN: 0163-1829 (Print)
Abstract: 
We study the quantum spin waves associated to skyrmion textures. We show that the zero-point energy associated to the quantum spin fluctuations of a noncollinear spin texture produce Casimir-like magnetic fields. We study the effect of these Casimir fields on the topologically protected noncollinear spin textures known as skyrmions. In a Heisenberg model with Dzyalonshinkii-Moriya interactions, chosen so the classical ground state displays skyrmion textures, we calculate the spin-wave spectrum, using the Holstein-Primakoff approximation, and the associated zero-point energy, to the lowest order in the spin-wave expansion. Our calculations are done both for the single-skyrmion case, for which we obtain a discrete set of skyrmion bound states, as well as for the skyrmion crystal, for which the resulting spectrum gives the spin-wave bands. In both cases, our calculations show that the Casimir magnetic field contributes up to 10% of the total Zeeman energy necessary to delete the skyrmion texture with an applied field.
Keywords:Spin waves, Quantum fluctuations, Skyrmion textures
American Physical Society
info:eu-repo/semantics/article