Spin-polarized scanning tunneling microscopy investigations reveal a significant increase of the magnetic period of spin spirals in three-atomic-layer-thick Fe films on Ir(111), from about 4nm at 8K to about 65nm at room temperature. We attribute this considerable influence of temperature on the magnetic length scale of noncollinear spin states to different exchange interaction coefficients in the different Fe layers. We thus propose a classical spin model which reproduces the experimental observations and in which the crucial feature is the presence of magnetically coupled atomic layers with different interaction strengths. This model might also apply for many other systems, especially magnetic multilayers.
@article{arxiv.1703.10849,
title = {Temperature-induced increase of spin spiral periods},
author = {Aurore Finco and Levente Rózsa and Pin-Jui Hsu and André Kubetzka and Elena Vedmedenko and Kirsten von Bergmann and Roland Wiesendanger},
journal= {arXiv preprint arXiv:1703.10849},
year = {2017}
}