arXiv subjects

S. R. Lake

Publications and source records attributed to S. R. Lake.

7 recordsLinked to original sources

arXiv2025

Highly efficient coherent amplification of zero-field spin waves in YIG nano-waveguides

Transmission and processing of information at the nanoscale using spin waves and their quanta - magnons, offers numerous advantages and opportunities that make it a promising next-generation technology for integrated electronics. The main challenges that still need to be addressed to ensure high competitiveness of magnonic devices include finding ways to efficiently amplify spin waves in nanostructures and developing nanocircuits that can operate without the need for an external bias magnetic field. Here we demonstrate how these two challenges can be solved using nano-waveguides fabricated from a low-loss magnetic insulator. We show that by using local parametric pumping with a power of only a few milliwatts, one can achieve coherent amplification of spin-wave pulses by more than two orders of magnitude at zero bias magnetic field. Our results provide a simple solution to problems that have long prevented the implementation of efficient integrated magnonic circuits.

cond-mat.mes-hall↗

arXiv2025

Resonant inter-mode second harmonic generation by backward spin waves in YIG nano-waveguides

We experimentally study nonlinear generation of the second harmonic by backward volume spin waves propagating in microscopic magnonic waveguides fabricated from a low-loss magnetic insulator with a thickness of several tens of nanometers. We show that highly efficient resonant second harmonic generation is possible in the inter-mode regime at microwave powers of the order of 10^-4 W. In contrast to previously observed second harmonic generation processes, the generation by backward waves is characterized by the nonlinearly generated waves propagating opposite to the initial waves, and can be realized at zero bias magnetic field.

cond-mat.mes-hall↗

arXiv2024

Resonant generation of propagating second-harmonic spin waves in nano-waveguides

Generation of second-harmonic waves is one of the universal nonlinear phenomena that have found numerous technical applications in many modern technologies, in particular, in photonics. This phenomenon also has great potential in the field of magnonics, which considers the use of spin waves in magnetic nanostructures to implement wave-based signal processing and computing. However, due to the strong frequency dependence of the phase velocity of spin waves, resonant phase-matched generation of second-harmonic spin waves has not yet been achieved in practice. Here, we show experimentally that such a process can be realized using a combination of different modes of nano-sized spin-wave waveguides based on low-damping magnetic insulators. We demonstrate that our approach enables efficient spatially-extended energy transfer between interacting waves, which can be controlled by the intensity of the initial wave and the static magnetic field. The demonstrated approach can be used for the generation of short-wavelength spin waves that are difficult to excite directly, as well as for the implementation of novel devices for magnonic logic and unconventional computing.

cond-mat.mes-hall↗

arXiv2024

Laser patterning of magnonic structure via local crystallization of Yittrium Iron Garnet

The fabrication and integration of high-quality structures of Yttrium Iron Garnet (YIG) is critical for magnonics.Films with excellent properties are obtained only on single crystal Gadolinium Gallium Garnet (GGG) substrates using high-temperature processes. The subsequent realization of magnonic structures via lithography and etching is not straightforward as it requires a tight control of the edge roughness, to avoid magnon scattering, and planarization in case of multilayer devices. In this work we describe a different approach based on local laser annealing of amorphous YIG films, avoiding the need for subjecting the entire sample to high thermal budgets and for physical etching. Starting from amorphous and paramagnetic YIG films grown by pulsed laser deposition at room temperature on GGG, a 405 nm laser is used for patterning arbitrary shaped ferrimagnetic structures by local crystallization. In thick films (160 nm) the laser induced surface corrugation prevents the propagation of spin-wave modes in patterned conduits. For thinner films (80 nm) coherent propagation is observed in 1.2 micron wide conduits displaying an attenuation length of 5 micron which is compatible with a damping coefficient of about 5e-3. Possible routes to achieve damping coefficients compatible with state-of-the art epitaxial YIG films are discussed.

physics.app-ph↗

arXiv2023

Zero-field spin waves in YIG nano-waveguides

Spin-wave based transmission and processing of information is a promising emerging nano-technology that can help overcome limitations of traditional electronics based on the transfer of electrical charge. Among the most important challenges for this technology is the implementation of spin-wave devices that can operate without the need for an external bias magnetic field. Here we experimentally demonstrate that this can be achieved using sub-micrometer wide spin-wave waveguides fabricated from ultrathin films of low-loss magnetic insulator - Yttrium Iron Garnet (YIG). We show that these waveguides exhibit a highly stable single-domain static magnetic configuration at zero field and support long-range propagation of spin waves with gigahertz frequencies. The experimental results are supported by micromagnetic simulations, which additionally provide information for optimization of zero-field guiding structures. Our findings create the basis for the development of energy-efficient zero-field spin-wave devices and circuits.

cond-mat.mes-hall↗

arXiv2022

Interplay between nonlinear spectral shift and nonlinear damping of spin waves in ultrathin YIG waveguides

We use the phase-resolved imaging to directly study the nonlinear modification of the wavelength of spin waves propagating in 100-nm thick, in-plane magnetized YIG waveguides. We show that, by using moderate microwave powers, one can realize spin waves with large amplitudes corresponding to precession angles in excess of 10 degrees and nonlinear wavelength variation of up to 18 percent in this system. We also find that, at large precession angles, the propagation of spin waves is strongly affected by the onset of nonlinear damping, which results in a strong spatial dependence of the wavelength. This effect leads to a spatially dependent controllability of the wavelength by the microwave power. Furthermore, it leads to the saturation of nonlinear spectral shift's effects several micrometers away from the excitation point. These findings are important for the development of nonlinear, integrated spin-wave signal processing devices and can be used to optimize their characteristics.

cond-mat.mes-hall↗

arXiv2021

Efficient geometrical control of spin waves in microscopic YIG waveguides

We study experimentally and by micromagnetic simulations the propagation of spin waves in 100-nm thick YIG waveguides, where the width linearly decreases from 2 to 0.5 micrometers over a transition region with varying length between 2.5 and 10 micrometers. We show that this geometry results in a down-conversion of the wavelength, enabling efficient generation of waves with wavelengths down to 350 nm. We also find that this geometry leads to a modification of the group velocity, allowing for almost-dispersionless propagation of spin-wave pulses. Moreover, we demonstrate that the influence of energy concentration outweighs that of damping in these YIG waveguides, resulting in an overall increase of the spin-wave intensity during propagation in the transition region. These findings can be utilized to improve the efficiency and functionality of magnonic devices which use spin waves as an information carrier.

cond-mat.mes-hall↗