Dissipative axion-isolated layered electronics

Based on the fundamental principles of quantum mechanics, scientists have managed to design and produce electronic devices with specialized functionalities by manipulating the internal degrees of freedom of charge carriers to regulate transport behavior. These quantum electronic devices outperform traditional semiconductor devices in terms of storing, processing and transmitting information, with the significant advantages of lower power consumption and higher efficiency. Currently, spintronics and valleytronics are two scenarios for constructing quantum electronic devices by manipulating spin and valley degree of freedom, respectively, showing great potential in the field of low-power devices and quantum computing. Nevertheless, spintronics and valleytronics still have limitations. In spintronics, the Datta-Das spin-field transistor, which achieves spin polarization reversal by controlling the current, has not been successfully prepared due to technical shortcomings. In Valleytronics, there is still no effective method to completely reverse the valley polarization between two energy valleys. Therefore, a widely discussed issue is to find a new degree of freedom beyond spin and valley to establish a suitable transport mechanism and build higher-performance electronic devices.

Recent experimental studies have demonstrated an anomalous, layer-polarized Hall effect occurring in the intrinsic antiferromagnetic axion insulator (AI) material MnBi₂These₄ (Nature 595, 521 (2021)). This progress has made people realize that in addition to spin and valley, the electron spatial degree of freedom (here referring to the layer degree of freedom) can also be flexibly controlled, which is to be used to construct new electronic devices. However, the layer-polarized charge transport is not topologically protected and has no significant advantages in terms of energy loss and work efficiency. Therefore, whether the layer degree of freedom can be manipulated without scattering using topologically protected elementary excitations is a key problem to be solved in the preparation of high-performance devices in layered electronics.

Recently, a research team led by Professor XC Xie and Professor Hua Jiang from the Interdisciplinary Center for Theoretical Physics and Information Science at Fudan University/International Center for Quantum Materials at Peking University conducted a theoretical study on the design of Layertronics devices in AI MnBi₂These₄In this study, the concept of “layertronics” was established and prototypes of layered filters, layered valves, and layered reversers were designed using chiral, layered-polarized, topological domain wall modes in MnBi.₂These₄ materials. Compared to spintronics and valleytronics, layertronics devices are more stable and consume less power, which can be used to encode, process and store information. These are feasible solutions for producing a new generation of high-performance, low-loss electronic devices. This work was published in issue 11 National Scientific Review in 2024 entitled “Lossless electronic layer in the MnBi axion insulator₂These₄“. Professor Jiang Hua of Fudan University and Postdoctoral Fellow Gong Ming of Peking University’s Boya Postdoctoral Program are co-corresponding authors, while Gong Ming and Postdoctoral Fellow Li Shuai of Soochow University are co-first authors. Other collaborators include Professor Cheng Shuguang of Northwest University.

These studies demonstrate that topologically protected, layer-polarized, one-dimensional domain wall modes occur on even-layer antiferromagnetic MnBi domain walls.₂These₄. The chirality of the modes is inextricably linked to the layer’s degree of freedom, which is the essence of scattering-free layer degree-of-freedom manipulation and Layertronics device design. With these one-dimensional domain wall modes, the research team proposes designs for three basic devices: layer filters, layer valves, and layer inverters (see Figure 1). Layer filters can be realized via a two-terminal device consisting of a single MnBi₂These₄ antiferromagnetic domain wall. When a positive or negative bias voltage is applied, chiral modes located on different surfaces participate in the transport, creating a layer-polarized electronic current that can be used to filter current signals carrying specific information about the layer. Layered valve devices can be fabricated by combining two MnBi pairs₂These₄ magnetic domain walls with oppositely chiral domain wall modes. By independently adjusting the Fermi energy of the magnetic domain walls, the layer-polarized current can be turned on and off. Finally, using the Chern insulator state in ferromagnetic MnBi₂These₄the chiral domain wall modes on the top and bottom surfaces can be coupled, enabling the construction of a layer-inverting device that inverts the biased current in the layer (converting the current between the top and bottom surfaces). These basic Layertronics device designs provide the theoretical basis for establishing Layertronics and the scatterless manipulation of the layer’s degree of freedom. This study examines in detail the key technological approaches for the experimental fabrication of Layertronics devices (see Figure 2).