Non-symmetric influences in the total electron yield X-ray magnetic circular dichroism signal in applied magnetic fields

Abstract

The total electron yield current is strongly influenced by external magnetic fields. As known before, this side effect can be slightly reduced by applied external bias voltages increasing the total sample drain current nearly up to saturation. Nevertheless those effects are not perfectly reduced in almost all X-ray Magnetic Circular Dichroism (XMCD) applications and are more prominent in very small XMCD signals, like O K edge spectra. We show that asymmetries in the total electron yield field response will result in XMCD offset signals, which are strongly photon energy dependent and follow the nonmagnetic absorption signal. A simple but effective method to prevent those offset signals, is the use of asymmetric magnetic fields. A quantitative analysis and a numerical reduction method for those offset signals are shown.