Parametric Generation of Propagating Spin Waves in Ultrathin Yttrium Iron Garnet Waveguides

Abstract

Herein, experimental demonstration of the parallel parametric generation of spin waves in a microscaled yttrium iron garnet waveguide with nanoscale thickness is presented. Using Brillouin light scattering microscopy, the parametric excitation of the first and second waveguide modes by a stripline microwave pumping source is observed. Micromagnetic simulations reveal the wave vector of the parametrically generated spin waves. Based on analytical calculations, which are in excellent agreement with experiments and simulations, it is proved that the spin‐wave radiation losses are the determinative term of the parametric instability threshold in this miniaturized system. The used method enables the direct excitation and amplification of nanometer spin waves dominated by exchange interactions. The presented results pave the way for integrated magnonics based on insulating nanomagnets.

Lumped circuit model for inductive antenna spin-wave transducers

“…In recent years, numerous experiments have been conducted to study spin waves in nanoscale magnetic structures. 15,24,[55][56][57] When such spin waves are excited by inductive antennas, the scaling behavior of the spin-wave impedance of the antenna-waveguide system is key to understand the experimental signals and their dependence on the device geometry and dimensions. The scaling behavior of the system can be divided in two parts: (i) the dependence of the spin-wave impedance on the antenna and waveguide dimensions and (ii) the power transfer between the electrical source and the spin-wave system, which depends on the entire equivalent circuit, as represented in Fig.…”

Bose–Einstein condensation of nonequilibrium magnons in confined systems

“…2a. A microwave pumping pulse with a duration of tpump = 50 ns with a carrier frequency of fp = 4.2 GHz is applied to the simulated microwave stripline (placed on top of the conduit) whose dynamic Oersted fields leads to parametric generation of the magnons at fp /2 = 2.1 GHz that is slightly below the FMR frequency [35,[36][37]. This process has been studied experimentally and numerically in Ref.…”

“…This process has been studied experimentally and numerically in Ref. [37]. After the pumping pulse, we let the system relax for trelax = 50 ns.…”

“…We analyze the data during the pumping and relaxation periods separately. More details about the simulations can be found in [34,37].…”

“…We first set the microwave current to irf = 12 mA, which produces a pumping field with an amplitude of µ0hp = 8.9 mT that is well above the threshold of the parametric generation of magnons in the system [37]. In Fig.…”