Higher order vortex gyrotropic modes in circular ferromagnetic nanodots.
Magnetic vortex that consists of an in-plane curling magnetization configuration and a needle-like core region with out-of-plane magnetization is known to be the ground state of geometrically confined submicron soft magnetic elements. Here magnetodynamics of relatively thick (50-100 nm) circular Ni80Fe20 dots were probed by broadband ferromagnetic resonance in the absence of external magnetic field. Spin excitation modes related to the thickness dependent vortex core gyrotropic dynamics were detected experimentally in the gigahertz frequency range. Both analytical theory and micromagnetic simulations revealed that these exchange dominated modes are flexure oscillations of the vortex core string with n = 0,1,2 nodes along the dot thickness. The intensity of the mode with n = 1 depends significantly on both dot thickness and diameter and in some cases is higher than the one of the uniform mode with n = 0. This opens promising perspectives in the area of spin transfer torque oscillators.
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore-117576, Singapore.
Junjia
J
Ding
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore-117576, Singapore.
Gleb N
GN
Kakazei
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore-117576, Singapore.
Xinming
X
Liu
1] Departamento de Física de Materiales, Facultad de Química, Universidad del País Vasco, 20018 San Sebastián, Spain [2] IKERBASQUE, the Basque Foundation for Science, 48011 Bilbao, Spain.
Konstantin Y
KY
Guslienko
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore-117576, Singapore.
Adekunle O
AO
Adeyeye