We have developed a high-pressure and multi-frequency electron spin resonance (ESR) system in the submillimeter wave region. The pressure is generated by the piston–cylinder pressure cell whose inner parts are all made of ceramics. The requirements for the inner parts of the pressure cell are toughness and transmission in the submillimeter wave region and they enable us to observe the transmitted light through a sample subjected to high pressure. It was found that both properties can be achieved by the combination of the inner parts made of the ZrO2-based ceramic and the Al2O3 ceramic. For the Shastry-Sutherland compound SrCu2(BO3)2, we observed the direct ESR transition from the singlet ground state to the first excited triplet sates at 1.5 GPa successfully in the frequency region from 300 to 700 GHz.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics