Precise magnetoresistance and Hall resistivity measurements in the diamond anvil cell

Abstract

An experimental system in combination with a technique for creating samples has been developed for conducting magnetotransport measurements of 3d ferromagnets as a function of temperature and pressure. Polycrystalline Ni0.985O0.015 thin film samples have been manufactured for experiments at zero pressure and in the diamond anvil cell (DAC) such that the contacts are of a predetermined size. This ensures that the placement of the leads in the pressure chamber of the DAC does not affect the quality of the measurement. Magnetoresistance and Hall resistivity measurements are preformed using the van der Pauw technique and the constant current method. The performance of the experimental apparatus is demonstrated by magnetotransport measurements of Ni0.985O0.015 thin films between 285 and 455 K in applied magnetic fields up to 10 T. The change in magnetic resistivity measured in the transverse configuration at zero pressure in the DAC, −0.0162(2) μΩ cm T−1 at 297 K, is observed to be negative and linear up to the maximum applied field. The extraordinary Hall coefficient measured at zero pressure and 297 K is found to be RE=−30.4(1)×10−10 m3 C−1.