  We report a low temperature measurement technique and magnetization data of a
quantum molecular spin, by implementing an on-chip SQUID technique. This
technique enables the SQUID magnetometery in high magnetic fields, up to 7
Tesla. The main challenges and the calibration process are detailed. The
measurement protocol is used to observe quantum tunneling jumps of the S=10
molecular magnet, Mn12-tBuAc. The effect of transverse field on the tunneling
splitting for this molecular system is addressed as well.
