  Temperature below 100 microKelvin is achieved in a customized cryogen-free
dilution refrigerator with a copper-nuclear demagnetization stage. The lowest
temperature of conduction electrons of the demagnetization stage is below 100
microKelvin as measured by a pulsed platinum NMR thermometer and the
temperature can remain below 100 microKelvin for over 10 hours. An up to 9 T
demagnetization magnetic field and an up to 12 T research magnetic field can be
controlled independently, provided by a coaxial room-temperature-bore
cryogen-free magnet.
