Magnon spintronics Chumak, A. V.; Vasyuchka, V. I.; Serga, A. A. ...
Nature physics,
06/2015, Letnik:
11, Številka:
6
Journal Article
Recenzirano
Magnon spintronics is the eld of spintronics concerned with structures, devices and circuits that use spin currents carried by magnons. Magnons are the quanta of spin waves: the dynamic ...eigen-excitations of a magnetically ordered body. Analogous to electric currents, magnon-based currents can be used to carry, transport and process information.
Magnonic crystals for data processing Chumak, A V; Serga, A A; Hillebrands, B
Journal of physics. D, Applied physics,
06/2017, Letnik:
50, Številka:
24
Journal Article
Recenzirano
Odprti dostop
Magnons (the quanta of spin waves) propagating in magnetic materials with wavelengths at the nanometer-scale and carrying information in the form of an angular momentum can be used as data carriers ...in next-generation, nano-sized low-loss information processing systems. In this respect, artificial magnetic materials with properties periodically varied in space, known as magnonic crystals, are especially promising for controlling and manipulating magnon currents. In this article, different approaches for the realization of static, reconfigurable, and dynamic magnonic crystals are presented along with a variety of novel wave phenomena discovered in these crystals. Special attention is devoted to the utilization of magnonic crystals for processing of analog and digital information.
An attractive direction in next-generation information processing is the development of systems employing particles or quasiparticles other than electrons--ideally with low dissipation--as ...information carriers. One such candidate is the magnon: the quasiparticle associated with the eigen-excitations of magnetic materials known as spin waves. The realization of single-chip all-magnon information systems demands the development of circuits in which magnon currents can be manipulated by magnons themselves. Using a magnonic crystal--an artificial magnetic material--to enhance nonlinear magnon-magnon interactions, we have succeeded in the realization of magnon-by-magnon control, and the development of a magnon transistor. We present a proof of concept three-terminal device fabricated from an electrically insulating magnetic material. We demonstrate that the density of magnons flowing from the transistor's source to its drain can be decreased three orders of magnitude by the injection of magnons into the transistor's gate.
Advances in coherent magnonics Pirro, Philipp; Vasyuchka, Vitaliy I.; Serga, Alexander A. ...
Nature reviews. Materials,
12/2021, Letnik:
6, Številka:
12
Journal Article
Recenzirano
Magnonics addresses the dynamic excitations of a magnetically ordered material. These excitations, referred to as spin waves and their quanta, magnons, are a powerful tool for information transport ...and processing on the microscale and nanoscale. The physics of spin waves is very rich, ranging from a coexistence between dipole–dipole interaction and symmetric and antisymmetric exchange interaction, to various types of interface effects, anisotropies and spin torques. Spin waves are easily driven into the nonlinear regime. They can be confined and guided, and they can be amplified. Spin waves may be generated with varying degrees of coherency, depending on the excitation method, and transport mechanisms range from diffusive to ballistic. In this Review, we address specifically coherent spin waves. Coherency enables, for instance, the design of interference-based, wave processing spin-wave devices. Thus, the field of magnonics is well suited for the implementation of wave-based computing devices, combining the excellent versatility, smallness, nonlinearity and external control it affords. Novel coherent states of matter, such as magnon Bose–Einstein condensates, enable a broad range of additional applications.The field of magnonics studies the dynamic excitations of a magnetically ordered material. This Review surveys coherent magnonics, discussing the design of spin-wave devices and the use of magnon Bose–Einstein condensates to enable a broad range of applications.
A macroscopic collective motion of a Bose-Einstein condensate (BEC) is commonly associated with phenomena such as superconductivity and superfluidity, often generalised by the term supercurrent. ...Another type of motion of a quantum condensate is second sound-a wave of condensate's parameters. Recently, we reported on the decay of a BEC of magnons caused by a supercurrent outflow of the BEC from the locally heated area of a room temperature magnetic film. Here, we present the observation of a macroscopic BEC transport mechanism related to the excitation of second sound. The condensed magnons, being propelled out of the heated area, form compact humps of BEC density, which propagate many hundreds of micrometers in the form of distinct second sound-Bogoliubov waves. This discovery advances the physics of quasiparticles and allows for the application of related transport phenomena for low-loss data transfer in magnon spintronics devices.
A supercurrent is a macroscopic effect of a phase-induced collective motion of a quantum condensate. So far, experimentally observed supercurrent phenomena such as superconductivity and superfluidity ...have been restricted to cryogenic temperatures. Here, we report on the discovery of a supercurrent in a Bose-Einstein magnon condensate prepared in a room-temperature ferrimagnetic film. The magnon condensate is formed in a parametrically pumped magnon gas and is subject to a thermal gradient created by local laser heating of the film. The appearance of the supercurrent, which is driven by a thermally induced phase shift in the condensate wavefunction, is evidenced by analysis of the temporal evolution of the magnon density measured by means of Brillouin light scattering spectroscopy. Our findings offer opportunities for the investigation of room-temperature macroscopic quantum phenomena and their potential applications at ambient conditions.
Bose-Einstein condensation is one of the most fascinating phenomena predicted by quantum mechanics. It involves the formation of a collective quantum state composed of identical particles with ...integer angular momentum (bosons), if the particle density exceeds a critical value. To achieve Bose-Einstein condensation, one can either decrease the temperature or increase the density of bosons. It has been predicted that a quasi-equilibrium system of bosons could undergo Bose-Einstein condensation even at relatively high temperatures, if the flow rate of energy pumped into the system exceeds a critical value. Here we report the observation of Bose-Einstein condensation in a gas of magnons at room temperature. Magnons are the quanta of magnetic excitations in a magnetically ordered ensemble of magnetic moments. In thermal equilibrium, they can be described by Bose-Einstein statistics with zero chemical potential and a temperature-dependent density. In the experiments presented here, we show that by using a technique of microwave pumping it is possible to excite additional magnons and to create a gas of quasi-equilibrium magnons with a non-zero chemical potential. With increasing pumping intensity, the chemical potential reaches the energy of the lowest magnon state, and a Bose condensate of magnons is formed.
We study the formation of a room temperature magnon Bose-Einstein condensate (BEC) in nanoscopic systems and demonstrate that its lifetime is influenced by the spatial confinement. We predict how ...dipolar interactions and nonlinear magnon scattering assist in the generation of a metastable magnon BEC in energy-quantized nanoscopic devices. We verify our prediction by a full numerical simulation of the Landau-Lisfhitz-Gilbert equation and demonstrate the generation of magnon BEC in confined insulating magnets of yttrium iron garnet. We directly map out the nonlinear magnon scattering processes behind this phase transition to show how fast quantized thermalization channels allow the BEC formation in confined structures. Based on our results, we discuss a new mechanism to manipulate the BEC lifetime in nanoscaled systems. Our study greatly extends the freedom to study dynamics of magnon BEC in realisitc systems and to design integrated circuits for BEC-based applications at room temperature.
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