Reversible Bilayer-Monolayer Restructuring of ultrathin FeO on Ru(0001)

Abstract

IBERTRIVA 2019 X Iberian Conference on Tribology – IBERTRIB, XI Iberian Vacuum Conference - RIVA, Seville, Spain,June 26-28Iron monoxide, FeO, has a simple cubic structure that along the direction is comprised of alternating hexagonal layers of iron and oxygen with an fcc sequence. In bulk form it is usually iron deficient, and it can be grown as an ultrathin film on a variety of metallic substrates, among them Ru(0001) [1,2]. Here we show how an incomplete ultrathin FeO filmon Ru(0001) can be reversibly restructured from bilayer to monolayer thickness by changing the background oxygen pressure at high temperature and thus the amount of oxygen adsorbed in the uncovered Ru areas. The growth and the evolution of the iron oxide film upon different treatments is followed in real time by low-energy electron microscopy (LEEM) in ultra-high vacuum. LEEM is a full-field technique where an electron beam is directed towards the surface under observation and the elastically backscattered electrons are used to form a magnified image by means of electrostatic and/or electromagnetic lenses. In this work we employ the two LEEM instruments available in Spain. Both of them have similar characteristics and are located at the Alba synchrotron [3] and at the Instituto de Química Fïsica ¿Rocasolano¿ respectively. References [1] B. Santos, E. Loginova, A. Mascaraque, A. Schmid, K. McCarty, J. de la Figuera, Structure and magnetism in ultrathin iron oxides characterized by low energy electron microscopy, J. Physics-Cond. Matt. 21 (2009) 314011. [2] I. Palacio, M. Monti, J.F. Marco, K.F. McCarty, J. de la Figuera, Initial stages of FeO growth on Ru(0001), J. Phys.: Condens. Matter. 25 (2013) 484001 [3] L. Aballe, M. Foerster, E. Pellegrin, J. Nicolas, S. Ferrer, The ALBA spectroscopic LEEM-PEEM experimental station: layout and performance, J Synchrotron Radiat. 22 (2015) 74