In-plane angular dependence of the spin-wave nonreciprocity of an ultrathin film with Dzyaloshinskii-Moriya interaction

Abstract

The nonreciprocal propagation of spin waves in an ultrathinPt/Co/Ni film has been measured by Brillouin light scattering. The frequency nonreciprocity, due to the interfacial Dzyaloshinskii-Moriya interaction (DMI), has a sinusoidal dependence on the in-plane angle between the magnon wavevector and the applied magnetic field. The results, which are in good agreement with analytical predictions reported earlier, yield a value of the DMI constant which is the same as that obtained previously from a study of the magnon dispersion relations. We have demonstrated that our magnon-dynamics based method can experimentally ascertain the DMI constant of multilayer thin films.

Spin Waves in Thin Films and Magnonic Crystals with Dzyaloshinskii–Moriya Interactions

“…It was also found that the frequency asymmetry exhibits a linear dependence as a function of k, and it becomes more pronounced when increasing the thickness of the heavy metal. The in-plane angular dependence of the frequency shift was also measured with BLS [73,75,86,87], which evidences a clear sinusoidal dependence with φ k , in agreement with Eq. 5.25, as predicted theoretically [96].…”

“…The first observation of nonreciprocal spin waves [16,68,69] caused by interfacial DMI was achieved by Zakeri et al [70,71] using the spin-polarized electron energy loss (SPEEL) experimental technique. A few years later, nonreciprocal spin waves were observed by means of BLS spectroscopy in several ferromagnet/heavy metal interfaces [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87]. In agreement with the results of Zakeri et al [70,71], these numerous experiments have shown that interfacial DMI creates a noticeable frequency asymmetry in the spin-wave dispersion of counterpropagating Damon-Eshbach (DE) spin waves.…”

“…In particular, this numerical technique can be used to calculate the spectrum of spin waves, and when a DMI is present, it reveals different properties characteristic of these systems, such as the spin-wave asymmetry. In this context, simulations have successfully supported theoretical formulations [80,96,97,99,[132][133][134][135][136][137] and experimental measurements [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87]138] on thin-film systems with a homogeneous DMI. A micromagnetic simulation is based on numerically discretizing the continuum description of the magnetic system into a mesh of magnetic moments whose arrangement depends on the discretization method.…”

Interfacial control of Dzyaloshinskii-Moriya interaction in heavy metal/ferromagnetic metal thin film heterostructures

“…We note that the value here is modest compared with that in the Pt/FM systems 19,20,22,23,31 . Nevertheless, the DMI on the annealed Ta/CoFeB structures is still of great interest for the study of skyrmions.…”

“…According to Equation 1, a linear correlation exists between and , where the slope is determined by 23,31 . To further avoid possible instrument frequency offsets in the frequency difference between Stokes and anti-Stokes peaks, we subtract the values obtained by reversing the applied field as described by the following equation.…”