Adsorption and dissociation of iron phthalocyanine on H/Si(111): Impact of van der Waals interactions and perspectives for subsurface doping

Abstract

The adsorption of iron phthalocyanine (FePc) on the passivated H/Si(111) surface is explored from first principles. We find that the organic molecule is predominantly physisorbed with a distance to the surface of 2.6 ± 0.1 Å and an adsorption energy of 1.55 ± 0.1 eV, but also exhibits sizable resonance with the underlying substrate. This establishes the present system as interesting mixed covalent-van-der-Waals-bound test case, which we use to compare the impact of different approaches to van-der-Waals interactions. (Spin-polarized) scanning tunneling microscopy (SP STM) images are simulated, selectively accessing different molecular orbitals via the applied bias voltage in the spirit of scanning tunneling spectroscopy. Comparison with experimental STM images reveals very good agreement. We report a significant magnetic contrast exceeding ±1 Å in the SP STM images for −2 and +1.5 V. Aiming for a magnetic functionalization of Si for possible spintronics applications, magnetic moments and binding energies of different (transition metal) atoms in the center of the Pc ring are presented, which particularly show that Fe is strongly bound in the molecule (about 9.6 eV). Finally, we discuss different mechanisms for subsurface Fe doping by room-temperature FePc deposition and point out two feasible reactions. Concomitantly, we identify the crucial role of a preceding destabilization of FePc, for instance, by pre-adsorbed H atoms, which subsequently strongly stabilize the final state of the reaction.

Correlated interface electron gas in infinite-layer nickelate versus cuprate films on SrTiO$_3$(001)

“…Wave functions and density were expanded into plane waves up to cutoff energies of 45 and 350 Ry, respectively. Ultrasoft pseudopotentials [40] as successfully employed in previous work [35][36][37][38][41][42][43][44][45], were used in conjunction with projector augmented wave datasets [46]. The Pr and Nd 4f electrons are frozen in the core, similar to previous studies involving Nd [4,13,19,34]; their explicit treatment leads to qualitatively similar results.…”

Competition of defect ordering and site disproportionation in strained LaCoO3 on SrTiO3 (001)

“…Wave functions and density were expanded into plane waves up to cutoff energies of 35 and 350 Ry, respectively. Ultrasoft pseudopotentials, 41 as successfully employed in previous work, 28,29,[42][43][44][45][46][47][48][49] were used, treating the La 5s, 5p, 5d, 6s, 6p, Co 3d, 4s, 4p, and O 2s, 2p atomic subshells as valence states. For La and Co a non-linear core correction 50 was included.…”

Fundamental difference in the electronic reconstruction of infinite-layer vs. perovskite neodymium nickelate films on SrTiO$_3$(001)

“…Wave functions and density were expanded into plane waves up to cutoff energies of 45 and 350 Ry, respectively. Ultrasoft pseudopotentials [27] as successfully employed in previous work [22][23][24][25][28][29][30], were used in conjunction with projector augmented wave datasets [31]. The Nd 4f electrons are frozen in the core [11,21].…”