Magnon Blocking Effect and Magnonic Skin Effect Shown in Antiferromagnetically Coupled Heterojunction

Spin waves, or magnons, as the elementary excitation of the magnetic system, can move spin angular energy, giving vast prospects for the Non-volatile, low-energy-consumption, high-speed, and small-size microelectronic devices in the post-Moore duration. Magnonics, including the generation, transportation, and control of magnons, has ended up being the most recent advancement instructions of spintronics as well as the emerging self-control of compressed matter physics.

In recent years, Prof. HAN Xiufeng’s research team at the Institute of Physics of the Chinese Academy of Sciences (CAS) has established a magnon shutoff with a core framework of magnetic insulator (MI)/ spacer(S)/ magnetic insulator (MI) (such as YIG/Au/YIG), a magnon joint (such as YIG/NiO/YIG) and also a magnetoelectric separator which can be utilized as magnon generator as well as magnon detector (such as Pt/YIG/Pt), aiming to make use of pure electric approaches as well as the change of the magnetic structures to properly control the generation and transportation of magnons, therefore to understand a 100% transmission switch on-off ratio of the magnon currents.

For that reason, a further extensive understanding of the transportation buildings of incoherent or meaningful magnons in an entirely electrically insulated magnon junction will undoubtedly end up being the vital physical basis for the growth of functional magnonic gadgets and circuits in the future.

In order to much better comprehend the mechanism of magnon transmission in magnon junction from the microscale, PHD trainee YAN Zhengren, Partner Professor WAN Caihua, as well as Prof. HAN Xiufeng researched the magnon transmission in the sandwich framework of ferromagnetic insulator (FMI)/ antiferromagnetic insulator (AFI)/ ferromagnetic insulators (FMI) by atomistic spin-model simulations.

They discovered that magnon collective impact (MJE) or magnon shutoff effect (MVE) could be duplicated, showing the magnetization-dependent magnon transmission. The MJE, as well as MVE, stem from the polarization of spin-wave.

Generally, spin-up (spin-down) latticeworks can accommodate right- (left-) handed circularly polarized magnons. While only right-handed circularly polarized magnons are preferred in FMI with upward magnetization, both left- and right-handed round polarizations are permitted in AFI owing to two spin-opposite lattices. This selection regulation thus makes the complete reflection of spin-wave occur when magnons attempt to diffuse into a spin latticework, which does not support their polarization.

For example, when right-handed round magnons in the spin-up region are infused right into the spin-down area, the option regulation would certainly cause low magnon transmission throughout the user interface. This sensation called the magnon obstructing effect shows that spin-wave polarization plays an essential role in magnon transmission.

Furthermore, in theory, they researched the spreading habits of spin waves at the interface of an antiferromagnetically paired heterojunction. It is revealed that the spin waves going through the interface are evanescent waves, and also, the case waves are all reflected, showing a magnetization-dependent magnon blocking impact in this framework.

The result shows that with the rise of the spin-wave frequency, the decay size lowers and the evanescent wave are much more concentrated at the interface, revealing a magnonic skin result similar to the skin impact of electromagnetic waves.

In addition, a favorable magnonic Goos-Hänchen shift of the reflected waves was additionally predicted. It can be recognized by a reliable representation of user interface change generated by the nonzero degeneration size of the evanescent waves.

In summary, the outcomes show that the efficient control of coherent/incoherent magnons by magnon joints originates from the absolute chirality of magnons in magnetic products. These discoveries confirm the physical basis of magnon tools to control magnon transportation efficiently and offer a brand-new development direction and technological course for the growth of pure magnon-type storage and reasoning gadgets.

Reference:  Z. R. Yan et al, Magnonic skin effect and magnon valve effect in an antiferromagnetically coupled heterojunction, Physical Review B (2021). DOI: 10.1103/PhysRevB.104.L020413