Dark soiitons of magnetostatic surface waves in magnetic films have been observed for the first time. The experiments were conducted at 5.19 GHz on 7.2 /im single-crystal yttrium iron garnet films. The dark soiitons were excited by 15 ns wide **off" pulses in a high power cw microwave signal applied to the film. The characteristic soliton narrowing effect in the output pulses was observed as the input power was increased above the 0.5-1 W threshold levels. The shape of the ''dark" pulse agrees with the |tanh| functional dependence predicted from theory. Direct measurements of the carrier signal showed a phase shift of close to 180° at the center of the dark soliton, also in agreement with theory.PACS numbers: 75.30.Ds, 76.50.+g, 85.70.Ge Envelope soiitons are nonlinear wave packets which preserve their shape without dispersive spreading. In recent years, soliton excitations have been realized in many physical systems [1-3]. One well-known example is the optical-envelope soliton in optical fiibers [4,5]. Envelope soiitons for spin waves at microwave frequencies have been observed in yttrium iron garnet (YIG) thin films for various magnetic field and propagation combinations, including forward-volume wave [6,7], surface wave [8], and backward-volume wave [9] configurations.The envelope of nonlinear spin wave packets propagating in ferromagnetic thin films has been found to be best described by the nonlinear Schrodinger (NLS) equation [10,11]. It is well known that the NLS equation has two different types of solutions which correspond to bright and dark soiitons, depending on the relative signs of the dispersion coeflficient and the nonlinearity coeflficient in the equation [12,13]. Bright soliton solutions exist when the product of these two coefficients is negative, while dark soliton solutions exist when the product is positive. All of the magnetic experiments to date have been for bright soiitons, that is, for normal propagating wave packets.This Letter reports the first observation of microwave magnetic-envelope dark soiitons and the first experimental verification of the 180° phase shift in the carrier signal at the center of the pulse for any category of NLS dark soliton. The experiments were done at 5.19 GHz on in-plane magnetized single-crystal YIG films. Both the output signal envelope and the actual carrier signal output were measured. For input power levels above a certain threshold in the range of 0.5-1 W, the output signal pulses showed a narrowing which is characteristic of dark soiitons and the carrier showed at 180° phase shift over the central minimum region, also characteristic of dark soiitons. These results are in quantitative agreement with the theoretical dark soliton solutions for the NLS equation [13].The propagating spin waves were excited in the magnetic thin film by applying cw microwave power to a magnetostatic wave (MSW) delay line structure using a microstrip transducer [14]. The width of the dark pulse was controlled by chopping the cw signal with a fast microwave switch. The cw si...

Microwave-magnetic-envelope (MME) solitons generated from nonlinear magnetostatic-backwardvolume wave packets have been observed in magnetic thin films. The MME signals were excited by 5-50-ns wide microwave pulses at 5.8 6Hz in a 15-mm-long by 2.5-mm-wide, 7.2-pm-thick single-crystal yttrium iron garnet {YIG) film strip magnetized in plane and parallel to the long side of the strip. The wave packets were propagated parallel to the static field. The wave packets were launched and the propagating MME pulse signals were detected with planar microstrip transducers 4 mm apart. Envelope soliton behavior was evident from the time-resolved wave forms observed for various input power and pulse width combinations. At low power levels, one sees a relatively broad output pulse which scales with the width of the input pulse and a peak power which increases linearly with the input power. As the input power is increased above some threshold in the 0.5-1-% range, output pulses show a narrowing and steepening which is characteristic of microwave-magnetic-envelope solitons. Further increases in input power produce multiple-peak profiles, characteristic of multiple soliton generation. The experimental results are consistent with the various characteristic times for linear and nonlinear MME pulse propagation and soliton formation. However, numerical modeling based on the magnetic form of the nonlinear Schrodinger equation with initial conditions and parameters which match the experiments yields calculated profiles which show soliton effects but do not quantitatively match the experimental results.

Magnetostatic forward volume wave (FVW) microwave magnetic envelope solitons in 7.2 pm thick, single-crystal yttrium-iron garnet films have been studied at 5.6-6.0 GHz. Rectangular input pulses with peak powers up to 3 W and pulse widths 5-50 ns were used. Single soliton output pulses with a characteristic increase in amplitude and pulse narrowing are observed when the power or width of the rectangular input microwave pulse exceeds threshold levels. Above these levels, output pulse peak power versus input power or pulse width exhibits a nonlinear increase and shows saturation effects. Multiple peak output profiles are observed for pulse powers and widths well above threshold. Solitons could be formed for all frequencies within the usable, low transmission loss portion of the magnetostatic FVW band. The use of reflected pulses from the film edge made it possible to study soliton decay and soliton collisions. The soliton decay rate was found to be approximately twice the linear rate, as expected from theory. The collision of solitons was found to occur with no significant change in shape and velocity. The various characteristic times from theory for pulse decay, pulse dispersion, nonlinear response, and propagation are found to be consistent with the experimental results.

Crystalline anisotropy and loss effects on magnetostatic waves in layered yttrium iron garnet films

Phase properties of microwave magnetic envelope dark solitons in yttrium iron garnet thin films (abstract) Forward volume wave microwave envelope solitons in yttrium iron garnet films: Propagation, decay, and collision J. Appl. Phys. 76, 4274 (1994); 10.1063/1.357312 Forward volume wave microwave envelope solitons in yttrium iron garnet thin films: Peak profiles and multisoliton signatures (abstract)