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

The total electron yield current is strongly influenced by external magneti c fields. As known before, this side effect can be slightly reduced by appl ied 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 mo re prominent in very small XMCD signals, like O K edge spectra. We show tha t asymmetries in the total electron yield field response will result in XMC D offset signals, which are strongly photon energy dependent and follow the nonmagnetic absorption signal. A simple but effective method to prevent th ose offset signals, is the use of asymmetric magnetic fields. A quantitativ e analysis and a numerical reduction method for those offset signals are sh own.