A HIGH-SENSITIVITY ALTERNATING-GRADIENT MAGNETOMETER FOR USE IN QUANTIFYING MAGNETIC FORCE MICROSCOPY

An extremely sensitive alternating gradient magnetometer (AGM) has been developed. This AGM has been designed as an aid in characterizing the response of magnetic force microscope tips to known magnetic fields and field gradients. It should also prove useful as a general purpose magnetometer for small samples. A sensitivity of approximately 1.4 x 10(-11) emu has been achieved. Minor improvements in vibration isolation should bring this number down to approximately 10(-12) emu. A sensitivity of approximately 10(-14) emu is theoretically possible. The capabilities of the AGM are illustrated with magnetization versus field data for an 8-mu-m Ni sphere.