Dependence of energy barrier reduction on collective excitations in square artificial spin ice: A comprehensive comparison of simulation techniques

Abstract

We perform micromagnetic simulations to study the switching barriers in square artificial spin ice systems consisting of elongated single domain magnetic islands arranged on a square lattice. By considering a double vertex composed of one central island and six nearest neighbor islands, we calculate the energy barriers between two types of double vertices by applying the simplified and improved string method. We investigate by means of micromagnetic simulations the consequences of the neighboring islands, the inhomogeneities in the magnetization of the islands and the reversal mechanisms on the energy barrier by comparing three different approaches with increasing complexity. The micromagnetic models, where the string method is applied, are compared to a method commonly in use, the mean barrier approximation. Our investigations indicate that a proper micromagnetic modeling of the switching process leads to significantly lower energy barriers, by up to 35% compared to the mean-barrier approximation, so decreasing the expected average life time up to seven orders of magnitude. Hereby, we investigate the influence of parallel switching channels and the conceptional approach of using a mean-barrier to calculate the corresponding rates.

Tension-free Dirac strings and steered magnetic charges in 3D artificial spin ice

“…According to the original definition of emergent magnetic monopoles, the energy required to create a monopoleantimonopole pair (charge separation), should be larger than the energy required to propagate it [6,10,16,[52][53][54]. We verify these properties by applying a full-micromagnetic model to calculate the energy barriers to separate and propagate the magnetic charges [48,55,56]. The detailed description of the full micromagnetic model and its application on 2DASIs is given in Ref.…”

“…We choose rotational magnetic ellipsoids as ASI elements, because the self-demagnetizing field of the ellipsoids is homogeneous thus keeping the magnetic elements uniformly magnetized in the direction of the longer axis with no edge inhomogeneities [46][47][48][49]. Hence, our model shows nearly perfect Ising behavior and is suitable to separate and host magnetic charges.…”

“…The detailed description of the full micromagnetic model and its application on 2DASIs is given in Ref. [48].…”

Thermoplasmonic Nanomagnetic Logic Gates

“…The energy barrier that must be overcome in the transition from state i to state j can be calculated with the mean-field barrier method [46] as…”

Thermally superactive artificial kagome spin ice structures obtained with the interfacial Dzyaloshinskii-Moriya interaction

“…As indicated by the results of micromagnetic simulations, shown in Fig. 2(a) and the Supplemental Material movies [20], a quasicoherent rotation governs the magnetization reversal as determined by minimum energy path simulations [24][25][26] using bulk Ni 80 Fe 20 parameters [27]. The energy associated with the intermediate state sets an energy barrier E B with the net magnetization momentarily pointing along the short axis of the nanomagnet.…”