Absolute measurements of the AC susceptibility of cylindrical samples of arbitrary aspect ratio: scaling of the external susceptibility

Summary form only given. Absolute values of the AC-susceptibility of a given material are usually obtained from measurements of the so-called external susceptibility of a sample which, to favor proper correction of demagnetizing effects, is frequently shaped as a cylinder or an ellipsoid of revolution. For long cylindrical samples, one may, alternatively, benefit from the fact that the one-dimensional problem of infinite cylinders has been addressed in the literature and used to relate the complex components of external and absolute susceptibilities. More recently, de Faria et al. have successfully extended the infinite cylinder case, deriving expressions for cylindrical samples of non-magnetic metals of any length in the low-frequency regime. In this contribution we report new results obtained for two sets of cylindrical samples: YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// and electrolytic copper. In both cases, the low-frequency absolute susceptibility is related to the external susceptibilities of finite length cylinders through a single scaling function. This behavior, which seems to be universal, proved to be very well fitted by the same governing function previously proposed by de Faria and co-workers. This study extends also to the very small length side of the range, indicating limiting conditions for the ratio between sample and pickup coil dimensions.