Developing spin light emitting diodes toward real optoelectronic applications

Spin light-emitting diodes (LEDs), which can convert carrier spin polarization into photon circular polarization, are essential building block of various spin-optoelectronic devices and have garnered significant interest over the past two decades. These devices enable high-speed electrical control of light polarization through spin-photon conversion and hold great potential for applications in optical communication, three-dimensional (3D) displays, biomedical analyses, and more. The concept of the spin-LED was first proposed in 1999 [1]. However, several challenges must be addressed to advance these applications, including (1) achieving high circular polarization through efficient spin injection, (2) eliminating the need for an external magnetic field, and (3) enabling electrical control of polarization. Our recent breakthroughs demonstrate that these three challenges can be overcome. My talk will present the state-of-the-art developments in spin-LEDs with a focus on our recent advancements in spin injectors that meet the three criteria: (1) high spin injection efficiency [2-4], (2) perpendicular magnetization anisotropy [5], and (3) electrical control of magnetization [6], thereby paving the way for the development of various spin-optoelectronic applications.



References:

[1] R. Fiederling, et al., Injection and detection of a spin-polarized current in a light-emitting diode, Nature 402, 787 (1999).

[2] P. Barate, et al., Bias Dependence of the Electrical Spin Injection into GaAs from Co-Fe-B/MgO Injectors with Different MgO Growth Processes, Phys. Rev. Appl. 8, 054027 (2017).

[3] A. E. Giba, et al. Spin Injection and Relaxation in p-Doped (In,Ga)As/GaAs Quantum-Dot Spin Light-Emitting Diode at Zero Magnetic Field, Phys. Rev. Appl. 14, 034017 (2020).

[4] F. Cadiz, et al., Electrical initialization of electron and nuclear spins in a single quantum dot at zero magnetic field, Nano Lett. 18, 2381 (2018).

[5] S. H. Liang, et al., Large and robust electrical spin injection into GaAs at zero magnetic field using an ultrathin CoFeB/MgO injector, Phys. Rev. B 90, 085310 (2014).

[6] P. A. Dainone, et al., Controlling the helicity of light by electrical magnetization switching, Nature 627, 783 (2024).