Suhl instabilities for spin waves in ferromagnetic nanostripes and ultrathin films

We observe that an rf microwave field strongly influences the transport of incoherent thermal magnons in yttrium iron garnet. Ferromagnetic resonance in the nonlinear regime suppresses thermal magnon transport by 95%. The transport is also modulated at non-resonant conditions in two cases, both related to the magnon band minimum. Firstly, a strong enhancement of the nonlocal signal appears at a static magnetic field below the resonance condition. This increase only occurs at one field polarity and can be as large as 800%. We attribute this effect to magnon kinetic processes, which give rise to band-minimum magnons and high-energy chiral surface modes. Secondly, the signal increases at a static field above the resonance condition, where the rf frequency coincides with the magnon band minimum. Our study gives insight into the interplay between coherent and incoherent spin dynamics: The rf field modifies the occupation of relevant magnon states and, via kinetic processes, the magnon spin transport. arXiv:1810.11667v1 [cond-mat.mes-hall]

show abstract

“…Until reaching a certain rf field for the given magnet, θ will not increase any more. This is called the Suhl saturation [43,44,55].…”

Section: Comparison Between the Rf Power Dependent R 1ωmentioning

confidence: 99%

Microwave control of thermal-magnon spin transport

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Let us investigate the observed nonlinear dynamics in the multi-mode conduit. In principle, a nonlinear scattering instability is characterized by a clear threshold of the initial magnon intensity which is required for its onset [18,22,24,42]. Neglecting SW radiation losses, the threshold magnon intensity is defined by the effective relaxation frequency of the unstable mode divided by the four-magnon coupling strength [16,22].…”

mentioning

confidence: 99%

Controlling the Nonlinear Relaxation of Quantized Propagating Magnons in Nanodevices

et al. 2021

View full text Add to dashboard Cite

“…with M x,y = M s (x)m x,y . A solution of the LLG equations for the complex spin wave amplitude a(X, τ ) that satisfies these boundary conditions can be written as: (15) where X ≡ x/c, k l = (2l − 1)π/2, and q l = lπ.…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…Magnetization dynamics in thin-film nanoscale ferromagnets is of fundamental and practical importance in the field of spintronics [1][2][3][4][5][6][7]. The spectrum of spin wave excitations in such nanomagnets is quantized due to geometric confinement [8,9], which gives rise to a plethora of interesting nonlinear magneto-dynamic effects not found in bulk ferromagnets [10][11][12][13][14][15][16]. However, calculations of the spin wave spectrum in such structures are challenging due to the importance of nonlocal dipolar interactions [17,18] and poor understanding of boundary conditions for dynamic magnetization at the nanomagnet edges [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Parametric resonance of spin waves in ferromagnetic nanowires tuned by spin Hall torque

Yang¹,

Jara²,

Duan³

et al. 2021

Preprint

View full text Add to dashboard Cite

We present a joint experimental and theoretical study of parametric resonance of spin wave eigenmodes in Ni80Fe20/Pt bilayer nanowires. Using electrically detected magnetic resonance, we measure the spectrum of spin wave eigenmodes in transversely magnetized nanowires and study parametric excitation of these eigenmodes by a microwave magnetic field. We also develop an analytical theory of spin wave eigenmodes and their parametric excitation in the nanowire geometry that takes into account magnetic dilution at the nanowire edges. We measure tuning of the parametric resonance threshold by antidamping spin Hall torque from a direct current for the edge and bulk eigenmodes, which allows us to independently evaluate frequency, damping and ellipticity of the modes. We find good agreement between theory and experiment for parametric resonance of the bulk eigenmodes but significant discrepancies arise for the edge modes. The data reveals that ellipticity of the edge modes is significantly lower than expected, which can be attributed to strong modification of magnetism at the nanowire edges. Our work demonstrates that parametric resonance of spin wave eigenmodes is a sensitive probe of magnetic properties at edges of thin-film nanomagnets.

show abstract

Suhl instabilities for spin waves in ferromagnetic nanostripes and ultrathin films

Cited by 13 publications

References 31 publications

Microwave control of thermal-magnon spin transport

Microwave control of thermal-magnon spin transport

Controlling the Nonlinear Relaxation of Quantized Propagating Magnons in Nanodevices

Parametric resonance of spin waves in ferromagnetic nanowires tuned by spin Hall torque

Contact Info

Product

Resources

About