Ferromagnetic Resonance in Manganese Arsenide

Letters to the Editor,.The dielectric strength of one film was measured at 15" C. and at 100" K.It increased from 8 x 108 v/cm.to 9.5 x IO8 vjcm.Similar results were found by von Hppel and Maurer (1941) using soda lime glass.This indicates that aluminium oxide has an amorphous structure and supports Hass' statement that no pores exist in the oxide film formed by anodization.The relationship between formation voltage and film thickness in the present experi- ments 1s similar to that found by Hass (1949) and by Giintherschulze and Betz (1936).It 1s linear, but wherean the latter obtained a slope of 11 A/VOlt and Hass 13 A/Volt, the present work gives 14 A/VOlt.