Terahertz Electron Spin Resonance Spectroscopy Using Broadband Frequency-Tunable Photomixers

Abstract In this review, we present a novel technique for terahertz (THz) electron spin resonance (ESR) spectroscopy using broadband frequency-tunable photomixers. These photomixers offer unique advantages, such as continuous and broadband frequency tunability, enabling high-resolution ESR spectroscopy in the THz region. Our technique can be applied to both field- and frequency-swept ESR setups, covering a wide frequency range of up to 1.1 THz and magnetic fields of up to 10 T. We also demonstrate an application to antiferromagnetic resonance spectroscopy. A comparison is made with other frequency-domain ESR techniques using continuous-wave and pulsed THz sources to emphasize the characteristics of our technique.