Influence of the Vertex Region on Spin Dynamics in Artificial Kagome Spin Ice

Abstract

We present experimental and theoretical studies of spin-wave mode dynamics in artificial Kagome spin ice vertices made of three identical 15-nm thick elongated Ni80Fe20 nano-islands (macrospins). We consider several possible configurations, from completely disjointed macrospins (full dipolar inter-element interactions) to fully jointed macrospins (full dipolar-exchange interactions). Using angular-resolved magnetic field dependent broadband ferromagnetic resonance (FMR), we demonstrate the occurrence of a mode localized in the vertex region as indicated by the distinct behavior of the FMR spectra at different angles and configurations. Theoretical calculations using micromagnetic simulations support the existence, origin, and behavior of this mode by interpreting it as a localized, quasi-uniform Kittel mode. Our findings pave the way for designing the most appropriate network consisting of ferromagnetic nanomagnets for specific application purposes in magnonics.

Tailoring magnetization reversal of a single-domain bar nanomagnet via its end geometry

“…In a real system consisting of bar nanomagnets, the applied external magnetic field may not always be directed along the long axes of all the bars. In all the aforementioned mesoscopic magnetic systems, such as in magnetic majority logic gates 1 , artificial spin ices [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and/or magnetic shape-morphing micromachines, the nanomagnets are patterned in various different orientations. Therefore, it is necessary to investigate the end geometry dependence of the magnetization reversal process of a single-domain nanomagnet under magnetic fields applied in different orientations.…”

“…Micromagnetic simulations of the magnetization reversal processes on a bar nanomagnetic were carried out using MuMax3 24 . The material parameters of permalloy (Ni80Fe20) were used in our investigation because it is a soft magnetic alloy with very large permeability, and more importantly, it is one of the most widely used materials in related research [1][2][3][4][5][6][7][8][9][10][11][12][15][16][17][18][19][20] . The material parameters were set as standard values widely used for permalloy [25][26][27][28][29][30] : the saturation magnetization (MS) is 8.6×10 5 A/m and the damping constant is 0.5 in order to quickly minimize the energy.…”

Angular-dependent dynamic response and magnetization reversal in Fibonacci-distorted kagome artificial spin ice

“…The competition between magnetostatic interactions among nearest-neighbor segments leads to degenerate ground states that follow the spin ice rule (SIR) similar to the original rule observed for atomic spins in the tetrahedral sublattice of pyrochlore spin ice [5]. In the last decade, researchers have studied ASI in variety of lattice types such as honeycomb (Kagome ASI) [6][7][8][9][10][11][12][13][14][15][16][17][18], square [19][20][21][22] and artificial quasicrystals [23][24][25][26][27][28][29].…”

“…FMR spectroscopy provides detailed information about magnetization texture and shape anisotropy of ASI. For example, magnetic shape anisotropy can be estimated from the slope of the frequency-field graph, df/dH (i.e., the steeper the slope, the stronger the shape anisotropy) [14]. We can also find the reversal fields for sublattices of segments by observing two or more discontinuities in f(H) or df/dH, or mode softening in f(H) [29].…”

Reconfigurable magnonic mode-hybridisation and spectral control in a bicomponent artificial spin ice

“…A subset of RMC has emerged based on artificial spin ice (ASI) arrays [17][18][19][20][21][22] where geometrical frustration gives rise to a vastly degenerate microstate space that features a long-range ordered ground state 23,24 and high-energy 'magnetic monopole'-like excited states 25,26 . The potential to leverage these states for their magnonic properties is great and studies into fundamentals of state-spectra correspondence [27][28][29][30][31][32][33] have set the scene for a new generation of ASI-based RMC designs. An open problem in the field is developing reliable, versatile and rapid means for microstate access.…”