Tuning the Structural, Electronic, and Magnetic Properties of Germanene by the Adsorption of 3$d$ Transition Metal Atoms

TL;DR

This study uses density functional theory to explore how adsorbing 3d transition metal atoms affects the structural, electronic, and magnetic properties of germanene, revealing potential for tunable magnetic and topological phases.

Contribution

It provides a comprehensive analysis of transition metal adsorption effects on germanene, including magnetic ordering and quantum anomalous Hall effect potential, which is novel for this 2D material.

Findings

V-adsorbed germanene can host quantum anomalous Hall effect

Different TM atoms induce ferromagnetic or antiferromagnetic orderings

Adsorption creates diverse electronic and magnetic states in germanene

Abstract

The structural, electronic, and magnetic properties of 3$d$ transition metal (TM) atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) adsorbed germanene are addressed using density functional theory. Based on the adsorption energy, TM atoms prefer to occupy at the hollow site for all the cases. The obtained values of the total magnetic moment vary from 0.97 $\mu_B$ to 4.95 $\mu_B$ in case of Sc to Mn-adsorption, respectively. A gap of 74 meV with a strongly enhanced splitting of 67 meV is obtained in case of Sc-adsorption, whereas metallic states are obtained in case of Ti, Cr, Mn, Fe, and Co. Non-magnetic states are realized for Ni, Cu, and Zn-adsorption. Moreover, semiconducting nature is obtained for non-magnetic cases with a gap of 26 to 28 meV. Importantly, it is found that V-adsorbed germanene can host the quantum anomalous Hall effect. The obtained results demonstrate that TM atoms and nearest neighbour Ge atoms are ferro-magnetically ordered in the cases of V, Mn, Fe, Co, Ni, Cu, and Zn, while anti-ferromagnetic ordering is obtained for Sc, Ti, and Cr. In addition, the effects of the coverage of all TM atoms on the electronic structure and the ferro-magnetic and anti-ferro-magnetic coupling in case of Mn are examined. The results could help to understand the effect of TM atoms in a new class of two-dimensional materials beyond graphene and silicene.