D. Valdaitsev

Investigation of a novel material for magnetoelectronics:Co2Cr0.6Fe0.4Al

Heusler compounds are promising candidates for future spintronics device applications. The electronic and magnetic properties of Co2Cr0.6Fe0.4Al, an electron-doped derivative of Co2CrAl, are investigated using circularly polarized synchrotron radiation and photoemission electron microscopy (PEEM). Element specific imaging reveals needle shaped Cr rich phases in a homogeneous bulk of the Heusler compound. The ferromagnetic domain structure is investigated on an element-resolved basis using x-ray magnetic circular dichroism (XMCD) contrast in PEEM. The structure is characterized by micrometre-size domains with a superimposed fine ripple structure; the lateral resolution in these images is about 100 nm. The domains look identical for Co and Fe giving evidence of a ferromagnetic coupling of these elements. No ferromagnetic contrast is observed at the Cr line. Magnetic spectroscopy exploiting XMCD reveals that the lack of magnetic moment, detected in a SQUID magnetometer, is mainly due to the moment of the Cr atom.

High‐pass energy‐filtered photoemission electron microscopy imaging of dopants in silicon

Differently doped areas in silicon can show strong electron‐optical contrast in dependence on the dopant concentration and surface conditions. Photoemission electron microscopy is a powerful surface‐sensitive technique suitable for fast imaging of doping‐induced contrast in semiconductors. We report on the observation of Si (100) samples with n‐ and p‐type doped patterns (with the dopant concentration varied from 1016 to 1019 cm−3) on a p‐ and n‐type substrate (doped to 1015 cm−3), respectively. A high‐pass energy filter of the entire image enabled us to obtain spectroscopic information, i.e. quantified photo threshold and related photoyield differences depending on the doping level. Measurements have confirmed the possibility of resolving areas at a high contrast even with the lowest dopant concentration when employing the energy filter. The influence of electron absorption phenomena on contrast formation is discussed.