Among varieties of THz ESR developments and applications [1], our multi-extreme THz ESR in Kobe can cover the frequency region between 0.03 and 7 THz [2], the temperature region between 1.8 and 300 K [2], the magnetic field region up to 55 T using the pulsed magnetic field [2], and the pressure region up to 1.5 GPa [3] simultaneously.
Moreover, the development of high-sensitive force-detected THz ESR achieved the measurements up to 1.1 THz using the micro-cantilever [4]. It is extended to the use of membrane-type surface stress sensor [5] and is applied to the microliter solution sample (myoglobin) [6]. Very recent development towards the high-sensitive THz ESR is the use of high power gyrotron plus membrane sensor [7], which will be presented at the conference.
For the high-pressure THz ESR, we have developed the hybrid-type pressure cell, and achieved 2.5 GPa under the steady magnetic field up to 10 T, 15 T at Kobe [8], and 25 T at the high field user facility in IMR, Tohoku University [9]. As applications of high-pressure THz ESR, the first-order pressure-induced transition was discovered at 1.85 GPa in the Shastry-Sutherland Model Compound SrCu2(BO3)2 [10], and the pressure dependence of exchange interactions was determined in triangular lattice antiferromagnet Cs2CuCl4, which shows several novel magnetic phase transitions under pressure [11]. Recently we have studied triangular antiferromagnet CsCuCl3 [12], which shows new pressure induced phase such as the magnetization plateau, and its THz ESR under pressure will be discussed. Finally, the application of thermal detection method [13] to THz ESR under pressure will be discussed at the conference.