Development of high-pressure, high-field and multi-frequency ESR apparatus and its application to quantum spin system

We have developed high-pressure, high-field and multi-frequency ESR apparatus. The pressure is available up to 14 kbar by using the clamped-type piston-cylinder pressure cell. All inner parts of the pressure cell are made of zirconia which has good transmittance of the electromagnetic wave in the frequency region from 70 to 700 GHz. The magnetic field region is up to 55 T and the temperature region is from 1.6 to 4.2 K. We present the results of quantum spin systems SrCu2(BO3)2 and CsCuCl3 as the application of this multi-extreme condition ESR technique and they will demonstrate its usefulness for studying the quantum spin system.