Magnetism of CrO overlayers on Fe(001)bcc surface: first principles calculations

Riva et al. [Surf. Sci. 621 , 55 (2014)] as well as Calloni et al. [J. Phys.: Condens. Matter 26 , 445001 (2014)] have studied the oxydation of Cr films deposited on Fe(001)bcc through low-energy electron diffraction, Auger electron spectroscopy and scanning tunneling microscopy. In the present work we perform a density functional approach within Quantum Expresso code in order to study structural and magnetic properties of CrO overlayers on Fe(001)bcc. The calculations are performed using DFT+U. The investigated systems include O/Cr/Fe(001)bcc, Cr/O/Fe(001)bcc, Cr 0.25 O 0.75 /Fe(001)bcc, as well as the O coverage O x /Cr/Fe(001)bcc ( x = 0.25; 0.50). We have found that the ordered CrO overlayer presents an antiferromagnetic coupling between Cr and Fe atoms. The O atoms are located closer to the Fe atoms of the surface than the Cr atoms. The ground state of the systems O/Cr/Fe(001)bcc and Cr/O/Fe(001)bcc corresponds to the O/Cr/Fe(001)bcc system with a magnetic coupling c (2 × 2). The effect of the O monolayer on Cr/Fe(001)bcc changes the ground state from p (1 × 1) ↓ to c (2 × 2) and produces an enhancement of the magnetic moments. The O x overlayer on Cr/Fe(001)bcc produces an enhancement of the Cr magnetic moments.