Magnetocaloric effect measurements in ultrahigh magnetic fields up to 120 T

We report proof-of-concept measurements of the magnetocaloric effect (MCE) in ultrahigh magnetic fields up to 120 T for the classical spin-ice compound Ho${}_2$Ti${}_2$O${}_7$. Radio-frequency resistivity measurements using an Au${}_{16}$Ge${}_{84}$ thin-film thermometer enable us to detect a rapid change in the sample temperature associated with a crystal-field level crossing in the high-field region in addition to a giant MCE at low fields. We discuss a possible delay in the temperature response and outline prospects for more precise MCE measurements in destructive pulsed fields.