Indirect chiral magnetic exchange through Dzyaloshinskii-Moriya-enhanced RKKY interactions in manganese oxide chains on Ir(100).

Localized electron spins can couple magnetically via the Ruderman-Kittel-Kasuya-Yosida interaction even if their wave functions lack direct overlap. Theory predicts that spin-orbit scattering leads to a Dzyaloshinskii-Moriya type enhancement of this indirect exchange interaction, giving rise to chiral exchange terms. Here we present a combined spin-polarized scanning tunneling microscopy, angle-resolved photoemission, and density functional theory study of MnO2 chains on Ir(100). Whereas we find antiferromagnetic Mn-Mn coupling along the chain, the inter-chain coupling across the non-magnetic Ir substrate turns out to be chiral with a 120° rotation between adjacent MnO2 chains. Calculations reveal that the Dzyaloshinskii-Moriya interaction results in spin spirals with a periodicity in agreement with experiment. Our findings confirm the existence of indirect chiral magnetic exchange, potentially giving rise to exotic phenomena, such as chiral spin-liquid states in spin ice systems or the emergence of new quasiparticles.

Citation

Schmitt, M., Moras, P., Bihlmayer, G., Cotsakis, R., Vogt, M., Kemmer, J., … Bode, M. (2019). Indirect chiral magnetic exchange through Dzyaloshinskii–Moriya-enhanced RKKY interactions in manganese oxide chains on Ir(100). Nature Communications, 10(1). doi:10.1038/s41467-019-10515-3

Acknowledgements

Experimental work was supported by DFG through FOR 1700 (project E6), SPP 2137 “Skyrmionics” (BO 1468/26-1), and by the Dresden-Würzburg Center for Topological Quantum Matter Research (ct.qmat). A.K.K. acknowledges receipt of a fellowship from the ICTP-TRIL Programme, Trieste, Italy.