Directional excitation of a high-density magnon gas using coherently driven spin waves

Abstract

Controlling magnon densities in magnetic materials enables driving spin transport in magnonic devices. We demonstrate the creation of large, out-of-equilibrium magnon densities in a thin-film magnetic insulator via microwave excitation of coherent spin waves and subsequent multi-magnon scattering. We image both the coherent spin waves and the resulting incoherent magnon gas using scanning-probe magnetometry based on electron spins in diamond. We find that the gas extends unidirectionally over hundreds of micrometers from the excitation stripline. Surprisingly, the gas density far exceeds that expected for a boson system following a Bose-Einstein distribution with a maximum value of the chemical potential. We characterize the momentum distribution of the gas by measuring the nanoscale spatial decay of the magnetic stray fields. Our results show that driving coherent spin waves leads to a strong out-of-equilibrium occupation of the spin-wave band, opening new possibilities for controlling spin transport and magnetic dynamics in target directions.

References in corpus (6)

• Measurements of the exchange stiffness of YIG films by microwave resonance techniques
• Propulsion of a domain wall in an antiferromagnet by magnons
• Optically coherent nitrogen-vacancy centers in μm-thin etched diamond membranes
• Magnon-Driven Domain-Wall Motion with the Dzyaloshinskii-Moriya Interaction
• Nanoscale Detection of Magnon Excitations with Variable Wavevectors Through a Quantum Spin Sensor
• Electrical Control of Coherent Spin Rotation of a Single-Spin Qubit

Cited by in corpus (9)

• Roadmap on Spin-Wave Computing
• A Fiber-coupled Scanning Magnetometer with Nitrogen-Vacancy Spins in a Diamond Nanobeam
• Filtering and imaging of frequency-degenerate spin waves using nanopositioning of a single-spin sensor
• Observation of spin-wave moiré edge and cavity modes in twisted magnetic lattices
• Roadmap on Quantum Magnetic Materials
• Multiplexed scanning microscopy with dual-qubit spin sensors
• Planar scanning probe microscopy enables vector magnetic field imaging at the nanoscale
• A robust, fiber-coupled scanning probe magnetometer using electron spins at the tip of a diamond nanobeam
• Quantitative imaging of nonlinear spin-wave propagation using diamond quantum sensors