High precision pick-up coils for pulsed field magnetization measurements

A pick-up system for precise magnetization measurements in pulsed field facilities is presented. Samples with diameters up to 5 mm can be measured (diameter of the pick-up coil is 6.8 mm, outer diameter of the pick-up system is 11.8 mm). The optimized geometry of the concentric pick-up and compensation coils reduces the influence of a sample displacement on the measured signal. The measured signal changes by less than 0.2% if the position of a spherical sample of 4.3 mm diameter is shifted by +/- 2mm along the axis of the coils. An additional compensation coil is used, to correct the difference between the winding areas of pick-up and compensation coils. This correction as well as the signal of the field measuring coils depend only weakly on an axial displacement of the pick-up system relatively to the center of the magnetic field. The calibration of the field measuring coils is performed by the metamagnetic transition of a MnF2 single crystal (H = 9.3 T at T = 4.2 K). The pick-up system is used for magnetization measurements in pulsed fields up to 50T at temperatures between 2 and 300K in the high magnetic field laboratory 'Hochfeldlabor Dresden'. (C) 2001 Elsevier Science B.V. All rights reserved.