Professor Kang Junyong, Professor Zhang Rong, and Professor Wu Yaping from Xiamen University's semiconductor research team have proposed a novel principle of orbital modulation for topological spin protection. They have successfully grown a lattice of magnetic quasi-particles (Merons) that are intrinsically stable at room temperature and exhibit long-range order under zero magnetic field conditions for the first time. Moreover, they have developed a Topological Spin Solid-State Light Emitting Diode (T-LED) chip. On July 13th, the related research findings were published in Nature Electronics. This achievement marks the first instance of chirality transfer from topologically protected quasi-particles to fermions and even bosons, thereby paving the way for new avenues in quantum state manipulation and transmission.
The schematic diagram of the topological spin solid-state light source chip developed by the team. Image courtesy of the research group.
Manipulating the spin angular momentum of photons to modulate the quantum state of light is a strategically advanced technology urgently needed in quantum science, 3D displays, bioimaging, and other fields. Traditional methods often require the introduction of optical elements such as polarizers and phase delay plates to control the phase of light sources, which are incompatible with existing microelectronic technologies, hindering the integration and miniaturization of information devices.
Efficient and miniaturized spin-polarized photon sources rely on effective control and transport of spin quantum states. Traditional spin control is demanding, requiring external magnetic fields or low-temperature environments, with low polarization rates, poor stability, and susceptibility to electromagnetic signal interference.
The team utilized their independently developed high magnetic field molecular beam epitaxy (HMF-MBE) device to obtain, for the first time, a Meron lattice with practical application value. They creatively applied topological spin structures to semiconductor devices, successfully utilizing topological protection to overcome the dependence on external magnetic fields and low-temperature conditions, innovatively developing the topological spin solid-state light source chip. This achievement represents a new breakthrough from theory to devices for topological materials, opening up a new field of intersection between optoelectronics and topological spin electronics.
The existing topological spin structures suffer from small scales and dependence on low temperature and external magnetic fields. Through theoretical simulations, the team predicted that a strong magnetic field during crystal growth could enhance and freeze d, s, p orbital coupling, potentially overcoming the growth bottleneck of large-area topological spin structures and achieving stability at room temperature and zero external fields.
Guided by this spark of idea, the team began their research and development from the equipment end, independently designing and building the HMF-MBE device. By optimizing the material system, they successfully grew large-scale, long-range ordered Meron lattices on wide-bandgap semiconductor substrates. This lattice exhibits high stability at room temperature without external magnetic fields, laying a solid foundation for the subsequent development of topological spin solid-state light source chips.
Topological spin structures are the carriers of future high-density, high-throughput, low-power information devices, yet their application exploration in the semiconductor optoelectronics field has not been conducted. Meanwhile, current research focuses on effectively controlling topological spin structures using light and spin currents (such as racetrack memory, skyrmion logic gates, etc.). The reverse process of "Can topological spin structures manipulate electrons and photons?" remains an unresolved mystery.
Through in-depth theoretical and experimental research, the team discovered that when electrons are injected into the Meron lattice, their transport orbitals can be effectively controlled, thereby generating spin polarization. Building upon this, the team further injected spin-polarized currents into quantum wells, completing the chiral transfer from topologically protected quasi-particles to electrons and then to photons, achieving efficient spin light emission. This novel topological spin solid-state light source chip is expected to meet the development needs of future quantum information technologies.
Related paper information: https://doi.org/10.1038/s41928-023-00990-4
