After brief introduction of history and facility of the High Magnetic Field Laboratory at KYOKUGEN in Osaka University, we describe our high field and multi-frequency electron spin resonance (ESR) apparatus by utilizing pulsed and superconducting magnets for the fields up to about 60 T. For the ESR measurements in pulsed magnetic fields, several Gunn and backward oscillators, and a far infrared laser are used as millimeter and submillimeter wave sources. In steady magnetic fields up to 16 T, we have utilized a vector network analyzer with extensions which covers the frequencies between 8 and 700 GHz almost continuously. The latter ESR apparatus is used not only dense magnetic materials but also weak ones, such as metalloproteins. Therefore, we have developed high sensitive multi-frequency ESR apparatus. To extend ESR studies further, we are now constructing ESR apparatus for much higher fields up to 70 T and the wide frequency range up to 7 THz. Magnetization and transport measurements are also performed in high magnetic fields up to 70 T and 60 T, respectively and magnetization measurements under high pressure up to 1 GPa. We plan to develop a 50 T wide bore pulsed magnet with the diameter of about 50 mm for the use of high sensitive ESR and high pressure measurements above 1 GPa.
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