SP-STM study of the multi-Q phases in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>GdRu</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Si</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Jonas Spethmann, N. D. Khanh, H. Yoshimochi, Rina Takagi, Satoru Hayami, Yukitoshi Motome, R. Wiesendanger, Shinichiro Seki, Kirsten von Bergmann
Abstract
The two stable surfaces of ${\mathrm{GdRu}}_{2}{\mathrm{Si}}_{2}$ are studied using spin-polarized scanning tunneling microscopy (SP-STM). Depending on the applied magnetic field different magnetic phases have been found and the presented measurements are in agreement with the respective previously proposed multi-$\mathbf{Q}$ spin textures. In particular, the multi-$\mathbf{Q}$ nature of the zero magnetic field state, for which previous experiments could not rule out the coexistence of single-$\mathbf{Q}$ states, can be confirmed by our spin-resolved measurements on the Si-terminated surface. The surfaces of ${\mathrm{GdRu}}_{2}{\mathrm{Si}}_{2}$ exhibit strong magnetism-induced modulations of the spin-averaged density of states. We find that while the magnetic contribution to the tunnel signal can be clearly identified for the Si-terminated surface this proves to be much more difficult for the Gd-terminated surface. However, the magnetic field dependent spatial modulations on the Gd-terminated surface demonstrate that additional magnetic phase transitions occur for the surface layer compared to those identified for bulk ${\mathrm{GdRu}}_{2}{\mathrm{Si}}_{2}$ and possible spin textures are presented.