Supporting Information
Tunable Magnetism on Si(111)-(2×1) via Chemisorption of
Graphene Nanoribbons
Zhuhua Zhang, Wanlin Guo, Xiao Cheng Zeng
Chemisorption configuration of other Z-GNRs on Si(111) and the corresponding
magnetic properties
(a)
(d)
Pd-6
(b)
(e)
Pl-6
Pd-7
(f)
(c)
Pl-7
Si
C
H
Figure S1 (a) Atomic structure of the clean Si(111)-2×1 surface. (b-e) The most
energetically favorable configurations of Z6- and Z7-GNRs chemisorbed on the Si
surface. We denote the configuration with ZN-GNR parallel to the silicon π-bond
chains (SPCs) as Pl-N, and that with ZN-GNR perpendicular to the SPCs as Pd-N. The
atoms belonging to SPCs are marked in red color. (f) Calculated electron localization
functions in a plane passing through two C-Si bonds for the configuration Pd-6 shown
in (d).
1
(a)
(c) 1.0
E-EF (eV)
0.5
(b)
0.0
-0.5
-1.0
J

J'
DOS (a.u.)
Figure S2 Magnetic properties of the Si(111) surface of the Pd-6. (a) Front and (b)
top views of the isosurface plots (0.005 e/Å3) of the magnetization density in the Si
substrate. Positive and negative magnetization densities are distinguished by cyan and
wine color, respectively. The chemisorbed Z6-GNR is removed in (b) and the Si
atoms bonding to the GNR are highlighted in dark blue. (c) Spin-polarized band
structures and density of states for Pd-6. The blue solid and red dot lines denote the
bands for the down- and up-spins, respectively.
(a) 1.0
(b)
E-EF (eV)
0.5
Si
0.0
Si
(c)
G
G
-0.5
-1.0
J

J'
Ribbon edge
Figure S3 Electronic and atomic properties of the Pd-7. (a) Band structure of the Pd-7,
the ground state of Pd-7 is nonmagnetic. (b) Side and (c) top views of the Pd-7
configuration. In this system, there is no dangling bond (DB) state, and all the Si
electron states are paired as the two Si-C bonds (denoted by red circles) are formed on
a high and a low Si atom in each SPC, respectively.
2
(c)
(a)
(d)
G
1.0
Si
D2
D1
(b)
G
Si
E-EF (eV)
J'
0.5

J
Figure S4 Magnetic and electronic properties for the Pl-7. (a) Front and (b) top views
of the isosurface plots (0.005 e/Å3) of magnetization density for Pl-7. The
0.0
chemisorbed Z7-GNR is removed and the silicon atoms bonding to the GNR are
highlighted in blue in (b) for clarity. (c) Spin-unpolarized and (d) spin-polarized band
structures for Pl-7. The blue solid and red dot lines denote the bands for the downand up-spins, respectively.
-0.5
Magnetism on Si(111) induced by adsorption hydrogen and fluorine
(a)

2
(b)
-1.0

J'
(c)
Figure S5 (a) Atomic structure of the Si(111) with a hydrogen atom chemisorbed on a
high Si atom in a SPC. (b) Plane-averaged charge density (red solid line) along the
[211] direction for the dangling-bond (DB) state induced by the chemisorbed H atom.
The partial charge density for the DB state is also shown in (b) and (c). In this case,
the system is nonmagnetic as the induced DB state is delocalized along the [211]
direction, even though it is confined along the [011] direction, as shown in (c).
3
(a)
(d)
(b)

2
DB1
(c)
0
7
DB2
14
21
28
x (angstrom)
35
Figure S6 (a) Atomic structure of the Si(111) with two hydrogen atoms chemisorbed
on two high Si atoms in a SPC. The two hydrogen atoms are the sixth
nearest-neighbors. (b) Top and (c) front views of the magnetization density (0.005
e/Å3) for the system. (d) Plane-averaged charge density (red solid lines) along the
[211] direction for two DB states induced by chemisorption of the two hydrogen
atoms. The corresponding partial charge densities are also shown as insets in (d). The
total moment is 0.63 μB.
4
(a)
Hydrogen
(b)
Hydrogen
(c)
Fluorine
Front view
Front view
Front view
Top view
Top view
Top view
Nonmagnetic semiconductor
Figure S7 (a) Atomic structure of the Si(111) with two hydrogen atoms chemisorbed
on an high Si atom and a low Si atom in a SPC, respectively. In this case, the system
is nonmagnetic. (b) Atomic structure and magnetization density of the Si(111) with
three hydrogen atoms chemisorbed in a SPC. Two of the hydrogen atoms are on two
high Si atoms while the rest one is on a low Si atom. The magnetization density is
located between the two hydrogenated high Si atoms. (c) Atomic structure and
magnetization density of the Si(111) with two fluorine atoms chemisorbed on two
high Si atoms in a SPC. The magnetization density is located between the two
fluorinated Si atoms. The chemisorbed atoms are marked by red circles in all the top
view figures.
(a)
(b)
Figure S8 (a) Top view of atomic structure of the Pd-4 with a Stone–Wales defect
near the left edge of the chemisorbed Z4-GNR. (b) Front view of corresponding
magnetization density of the structure shown in (a).
5