Half-metallicity and spin-polarization transport properties in
transition-metal atoms single-edge-terminated zigzag
a
-graphyne
nanoribbons
Mingjun Li
a
,
b
, Dan Zhang
b
, Yongli Gao
b
,
c
, Can Cao
b
, Mengqiu Long
b
,
*
a
School of Material Science and Engineering, Central South University, Changsha 410083, PR China
b
Institute of Super-microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha
410083, China
c
Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA
article info
Article history:
Received 27 November 2016
Received in revised form
13 February 2017
Accepted 14 February 2017
Available online 16 February 2017
Keywords:
Zigzag
a
-graphyne nanoribbons (Z
a
GyNRs)
3d transition-metal termination
Spin-polarized density functional theory
Half-metal
Spin-polarization
Negative differential resistance
abstract
By employing the non-equilibrium Green's function method a nd the spin-polarized density functional
theory, we investigate d the spin-resolved electronic transport properties of the zigz ag
a
-graphyne
nanoribbons (Z
a
GyNRs) pas sivated with 3d transition-metal atoms at one of the ribbon edge. Our
results exhibit half-metallic behavior in response to the Fe- , Co- and Ni-doping at the edge of Z
a
GyNRs.
The 3d transition-metal edge in troduced in this paper can result in large spin polarization on currents
of the Z
a
GyNRs devices, and som e interesting phenomena suc h as half-metallicity, spin-polarization
effect and negative differential resistance behavi or can be observed. These theoretical results suggest a
rout e to manipulate the spin-resolved electronic transport properties in Z
a
GyNRs-based spintronics
devices.
© 2017 Elsevier B.V. All rights reserved.
1. Introduction
Two-dimensional (2D) nano-materials have attracted great
attentions due to their unique electronic properties and wide
range of promising technological utilizations [1 e4]. Manipulating
the physical properties of 2D monolayer sheets such as graphene
through adsorbing transition metal (TM) is an important ch al-
lenge for realizing their application i n spintronics and nano-
electronics [5e9]. Graphene exhibits m any remarkable propert ies
[10,11], such as Dirac cone [12], high carrier mobility at room
temperature [13], Quantum spin Hall effect [14], and many other
novel phenomena and e lectronic properties [15]. Graphene has
also been extensively explored for inducing electronic spin po-
larization by chemical functionalization and doping [16e19].
However, the gapless band structure of graphene limits its
application in electron ic devices. Recently, graphyne, a nano ma-
terial isostructural graphene, has ignited substantial interests
owing to their extraordinary electroni c, optical, and structural
properties [20,21].
Although a single sheet of graphyne has still not been available,
it is a highly challenging task now. Nevertheless, in 2010, large
area films (~3.6 cm
2
) of graphdiyne (an allotrope of graphyne)
have b een successfully fabricated on a copper surface by a cross
cou pling reaction using hexaethynylbenzene [22], which is a big
step towards the preparation of graphynes, and encouraging
continuous effort for more extended struc tures. Graphyne is
composed of sp- and sp
2
-hybri zed ca rbon atoms, which can pro-
vid e an extra flexibility in modulation of its structure. Unlike
graphene , graphyne is a semiconductor with a narrow ban d gap,
which may provide a golden opportunity to use them in electronic
device [23,24]. Graphyne has many allotropes such as
a
-graphyne,
b
-graphyne,
g
-graphyne, and graphdiyne [25,26] .Andthetheo-
retical researches have been demonstrated that these graphynes
are assumed to be chemically stable [27]. Malko et al. found that
a
-graphyne is a new di rac cone material, which electronic p rop-
erties of
a
-graphyne is quite similar to that of graphene [28,29].
Similar to graphene nanoribbons (GNRs), the
a
-graphyne can also
be tailored into nanoribbons, and can be mainly classified into two
* Corresponding author.
E-mail address: mqlong@csu.edu.cn (M. Long).
Contents lists available at ScienceDirect
Organic Electronics
journal homepage: www.elsevier.com/locate/orgel
http://dx.doi.org/10.1016/j.orgel.2017.02.018
1566-1199/© 2017 Elsevier B.V. All rights reserved.
Organic Electronics 44 (2017) 168e175