Covalent nitrophenyl diazonium functionalized silicene for spintronics: a first-principles study

Abstract

We predict some novel electronic and magnetic properties of a functionalized silicene sheet by nitrophenyl diazonium (NPD) using first-principles calculations in the framework of density functional theory with dispersion corrections. Our calculations at the HSE06 level show that for the three coverage ratios of NPD considered in this work (i.e., NPD : Si = 1 : 8, 1 : 18 and 1 : 32), spin-polarized electronic structures can be always realized with NPD adsorption although the bandgap decreases upon reducing the NPD coverage ratio. The quasi-localized pz electrons of Si are identified to be responsible for the ferrimagnetism in these two-dimensional systems. Remarkably, the system with the NPD : Si = 1 : 8 ratio is predicted to be a bipolar magnetic semiconductor. As such, half-metallicity can be realized by applying a gate voltage with reversible spin polarization, making NPD-1/8 a potential candidate for future spintronic applications. This work offers a new tailor-made functionalization approach to realize magnetic semiconducting silicene.

Silicene: Recent theoretical advances

“…83 On the other hand, Ag is predicted to preserve a gapless Dirac cone. 84 The magnetism and the band gap can also be tuned by the adsorption of organic molecules [85][86][87] and superhalogen. 88 The fact that silicene stabilizes the catalytically active planar Au 20 cluster due to the strong covalent interaction can change the landscape of Au-based catalysts.…”

Chemical modification of group IV graphene analogs

“…Functionalization of silicane with different molecular fragments has included a variety of organic groups such as modification of the surface with hydroxyl (OH) [ 102 ], methyl (CH 3 ) [ 102,111 ], phenyl (C 5 H 5 ) [ 112–114 ], phenol (C 5 H 5 OH) [115], naphthyl [ 116 ], anthracyl [ 116 ] 2-(dimethylamino)ethanol or deanol (OCH 2 CH 2 NH(CH 3 ) 2 ) [ 117 ], acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), styrene (C 6 H 5 CH=CH 2 ) [ 118 ], hexyl (C 6 H 13 ) [ 111 ], propyl (CH 2 -CH 2 -CH 3 ), amine (CH 3 CH 2 NH 2 ), and ethoxy (CH 3 CH 2 O) [ 114 ] nitrophenyl diazonium [ 119 ]. A summary of these studies, along with their calculated band gaps is presented in Table 2 .…”

“…Functionalization of silicane with acetylene, ethylene, styrene [ 120 ], propyl-, amine-, and ethoxy-groups [ 114 ], and nitrophenyl diazonium [ 119 ] has also been considered, and the products were predicted to be semiconductors. Further details of these functionalized silicanes have been reviewed previously [ 97 ].…”

Functionalization of group-14 two-dimensional materials

“…Its family member, iron phthalocyanine (FePc) has been deposited on silicene/ZrB 2 and was shown to remain stable up to room temperature at the same time retaining its electronic states [198]. Nitrophenyl diazonium (NPD) on silicene is another example of functionalized system in which each NPD functional group is doped by 0.65 e, and exhibits spinpolarized ferrimagnetism [199]. Ionic liquids (IL)-attractive alternatives to conventional organic solvents-were shown to interact more strongly with silicene and germanene than with graphene or boron-nitride [200].…”