Ab initio study of magnetic nanopatterning of a hybrid transition metal dichalcogenides/Ir(111) system via magnetic clusters

Vasile Caciuc, Nicolae Atodiresei, and Stefan Blügel

Phys. Rev. Materials 3, 094002 – Published 9 September 2019

Abstract

In this theoretical study we scrutinized how the interaction between a magnetic cluster made of three Fe atoms and a ${MoS}_{2}$ monolayer adsorbed on Ir(111) reciprocally modifies their structural, electronic, and magnetic properties. From the structural point of view, the sulfur atom directly coordinated by the Fe cluster is pulled out of ${MoS}_{2}$ on Ir(111) while this behavior is not present for a freestanding ${MoS}_{2}$ single layer. Interestingly, this observation implies that Ir(111) catalyzes such a structural change in ${MoS}_{2}$ upon the magnetic cluster adsorption. Besides this, from the magnetic point of view, the sulfur atom lifted from the transition metal dichalcogenide (TMD) monolayer acquires a small magnetic moment and forms together with the Fe atoms a reactive local heterogeneous chalcogene–transition metal magnetic unit that can be employed to functionalize TMD-based hybrid systems.

Received 29 March 2019
Revised 18 July 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.3.094002

Physics Subject Headings (PhySH)

Density of states Electronic structure Exchange interaction Magnetism

2-dimensional systems Nanoclusters Transition metal dichalcogenides

Density functional theory First-principles calculations

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Vasile Caciuc ^*, Nicolae Atodiresei^†, and Stefan Blügel

Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany

^*v.caciuc@fz-juelich.de
^†n.atodiresei@fz-juelich.de

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 3, Iss. 9 — September 2019

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Top (a) and lateral (b) views of the ground-state adsorption geometry for a three-atom Fe cluster adsorbed on $(2 \sqrt{3} \times 2 \sqrt{3}) {MoS}_{2} / (4 \times 4) Ir (111)$ . Interestingly, the lateral view of this structure shows the presence of a sulfur atom relaxed out of the atomic plane of the Fe cluster [hereafter denoted as $S_{out}$ and the resulting configuration is referred to as $S_{out} / {Fe}_{3} / {MoS}_{2} / Ir (111)$ ]. It is important to mention that this behavior was also observed when a second ${Fe}_{3}$ cluster was deposited on substrate as shown in (c) and (d). These figures were obtained using VESTA [43].
Reuse & Permissions
Figure 2
(a) The spin-polarized atom-projected density of states (SP-PDOS) for the electronic states of the sulfur $S_{out}$ atom pulled out of the TMD surface by its interaction with the ${Fe}_{3}$ cluster and (b) the corresponding total and out-of-plane ( $d_{y z} + d_{z^{2}} + d_{x z}$ ) $d$ states of the Fe atoms as well as (c) of their three nearest-neighbor Mo atoms. It is important to note the hybridization between the $s p^{3}$ atomic-like hybrid orbitals of $S_{out}$ with the $d$ states of the Fe atoms. This observation is in particular apparent for the electronic states in an energy range of [ $E_{F} - 1.0$ eV, $E_{F}$ ]. Moreover, the spin-dependent interaction between the Fe and their three neighboring Mo atoms induces spin-polarized features in the electronic structure of these Mo atoms.
Reuse & Permissions
Figure 3
Lateral views of the real-space distribution (a) of the spin polarization density and (b) the spin polarization density difference plotted for the Fe cluster/ ${MoS}_{2} / Ir (111)$ system (isosurface of 0.038 electrons/ $Å^{3}$ ). Note that the spin polarization density $ρ_{polariz} = ρ^{↑} - ρ^{↓}$ is defined as the difference between the spin-up ( $ρ^{↑}$ ) and spin-down ( $ρ^{↓}$ ) densities while the spin polarization density difference is defined as $Δ ρ_{polariz} = ρ_{polariz}^{system} - ρ_{polariz}^{S_{out} / {MoS}_{2} / Ir (111)} - ρ_{polariz}^{{Fe}_{3}}$ , i.e., the difference between the spin polarization of the hybrid $S_{out} / {Fe}_{3} / {MoS}_{2} / Ir (111)$ system and those of the $S_{out} / {MoS}_{2} / Ir (111)$ and ${Fe}_{3}$ cluster with their geometry as in the hybrid system. As a general feature, note the presence of a positive spin density at the sulfur $S_{out}$ atom coupled ferromagnetically to the three Fe atoms. Interestingly, this feature at $S_{out}$ arises from the depletion of the spin density around the cluster Fe atoms and corresponds to a reduction of the magnetic moment from $\sim 3 μ_{B}$ for the freestanding ${Fe}_{3}$ cluster to $2.66 μ_{B}$ (per Fe atom) in the case of the hybrid system. The positive spin density is colored in yellow and the negative one in blue.
Reuse & Permissions
Figure 4
The band structures calculated for (a), (c) ${MoS}_{2} / Ir (111)$ and (b), (d) $S_{out} / {Fe}_{3} / {MoS}_{2} / Ir (111)$ including the spin-orbit coupling (SOC). The positive and negative spin polarization is indicated by red and blue symbols, respectively, for values larger than 2% when the spin polarization is summed over all atoms in the ${MoS}_{2}$ layer (the size of the symbols is proportional to the degree of spin polarization). In the case of ${MoS}_{2} / Ir (111)$ it is worthwhile to recall that the spin polarization of the ${MoS}_{2}$ layer becomes inverted along the $\bar{Γ} − \bar{K^{'}} − \bar{K} − \bar{Γ}$ direction when crossing through the $\bar{M}$ high-symmetry $k$ point as in the case of the freestanding ( $1 \times 1$ ) ${MoS}_{2}$ monolayer due to the time-reversal symmetry. However, in contrast to the freestanding ${MoS}_{2}$ monolayer, the hybridization between the ${MoS}_{2}$ and Ir(111) electronic states leads to SOC bands characterized by a spin-up or spin-down polarization with in general different weights at each $k$ point [see the zoom-in shown in (c)]. Besides this, as clearly depicted in (d), the interaction of the ${Fe}_{3}$ magnetic cluster with the ${MoS}_{2} / Ir (111)$ substrate increases the magnitude of the positive spin polarization in the ${MoS}_{2}$ layer at $\bar{K^{'}}$ and decreases it at $\bar{K}$ for the electronic states near the Fermi energy.
Reuse & Permissions

Physical Review Materials