SUPER-FERROMAGNETISM OF IRON DISILICIDE NANO-ISLANDS
Materials Science and Engineering, Tel Aviv univeristy, Tel-Aviv, Israel
We demonstrate control over super-magnetic response of tetragonal iron disilicide epitaxial and coherent nano islands on vicinal Si(111) surfaces. We utilize two epitaxial growth modes - solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE) - to grow structurally equivalent but morphologically different iron disilicide nano islands: orientated, ordered matrix vs. isotropic and randomly scattered. The structure and chemistry of these surfaces is investigated using scanning tunneling microscopy (STM), low energy electron diffraction (LEED), x-ray photo-electron spectroscopy (XPS), and transmission electron microscopy (TEM). The effect of surface arrangement on magnetic response is studied using superconducting quantum interference device (SQUID) magnetometry. We show that the periodic ordering of the islands along the vicinal surface of the Si(111) substrate is the primer reason for the emergence of the superferromagnetic behavior of the islands; who are otherwise superparamagnetic.
Tel Aviv University