Ohta, H., S. Okubo, E. Ohmichi, H. Takahashi, and T. Sakurai. “What Is Multi-Extreme THz ESR? Developments and Its Applications.” Applied Magnetic Resonance, October 25, 2024.
https://doi.org/10.1007/s00723-024-01722-3.
This review explores the multi-extreme THz ESR system in Kobe, Japan, with a focus on pulsed magnetic fields, mechanical detection, and high pressure as central elements of multi-extreme THz ESR. Initially, it discusses the advantages of multi-frequency THz ESR using mini-pulsed and 55 T‒pulsed magnetic fields, with typical examples featuring the finite Haldane chain substance Y 2BaNi0.96Mg0.04O5 and the deformed diamond chain antiferromagnet Cu3(CO3)2(OH)2 (Azurite). The measurement efficiency and the measurement beyond the magnetic phase transition, in contrast to the conventional superconducting magnet, are discussed. Second, the high sensitivity obtained from the use of a nano-membrane for mechanical detection is shown. Also shown are the high-temperature (280 K) THz ESR results for DPPH powder and a Cu(C4H4N2)(NO3)2 (CuPzN) single crystal, with the combination of a nano-membrane device and a high-power source, a gyrotron. Finally, the high-pressure THz ESR results for KCuCl3 using a transmission-type double-layered pressure cell are shown, along with the application of the thermally detected high-pressure THz ESR.