Influence of thickness and domain structure on the vortex instability of superconducting / ferromagnetic bilayers.

G. BLATTER; M. SIRENA; YEONKYU LEE; JINYOUNG YUN; JEEHOON KIM; E. DE BIASI; N. HABERKORN

SUPERCONDUCTOR SCIENCE AND TECHNOLOGY

IOP PUBLISHING LTD

Lugar: Londres; Año: 2024 vol. 39 p. 35007 - 35013

0953-2048

We report on the vortex instability in superconducting/ferromagnetic bilayers. Samples consisting of a 23 nm thick Mo2N superconducting layer with a capping layer of Co, Fe20Ni80, or FePt ferromagnets were grown by sputtering at room temperature on silicon (100). Our study reveals that the critical vortex velocity in these superconducting bilayers is significantly influenced by the thickness of the ferromagnetic layers rather than the specific magnetic domain structure. When comparing samples with ferromagnetic layers of 10 nm and 50 nm thickness, we observe a notable increase in vortex velocities at low magnetic fields, with speeds rising from approximately 3.5 km/s to around 6 km/s as the thickness increases. This trend extends to moderate and high magnetic fields. Furthermore, we establish a direct correlation between vortex velocities and the thermal conductance of the ferromagnetic layers. These findings provide valuable insights for the interplay of magnetic and thermal properties within these hybrid systems, with potential implications for the design of future devices and applications.