Elsevier

Organic Electronics

Volume 48, September 2017, Pages 357-364
Organic Electronics

The spin-charge transport properties for a graphene-based molecular junction: A first-principles study

https://doi.org/10.1016/j.orgel.2017.06.036Get rights and content

Highlights

  • First study on spin-charge transport for PAH molecular between ZGNR electrodes.

  • Multi-functions of perfect spin-filtering and –rectifying, GMR and NDR effects.

  • Functionalities adjusted by oxygen, electrode magnetic orientations and molecule-pyridine connection.

  • 3D illustration for spin-resolved transmission as a function of both energy and bias.

Abstract

We study the electron spin-charge transport properties through an aromatic molecule between two pyridines in conjunction with graphene electrodes by applying the nonequilibrium Green's functions in combination with the density functional theory. The computational result shows that, the multi-functions of perfect spin-filtering and spin-rectifying with efficiency approaching nearly 100%, giant magnetoresistance with ratio up to 105 and negative differential resistance effects, are exhibited in this all-carbon system. Importantly, these functionalities can be qualitatively adjusted by the oxygen absorption on molecule, the variation of the electrode initial magnetic orientations and the molecule-pyridine connection, respectively. The physical and chemical mechanisms are revealed and discussed in terms of the spin-resolved transmission spectrum, the evolution of the frontier molecular orbitals, the local density of states around the Fermi level at zero bias, and the molecular projected self-consistent Hamiltonian. Our conclusion may indicate a direction for designing all-carbon spintronic nanodevices based on graphene.

Introduction

In recent years, molecular spintronics is a thriving field driven by advances in shrinking electronic devices using molecules and by extraordinary properties of spin-charge transport [1], [2], [3]. Spintronic devices have broad potential application in many fields, such as data storage [4] and logical operation [5]. Moreover, a number of interesting spin-related phenomena have been observed in spintronic devices, including spin-crossover [6], [7], spin-filtering [8], [9], [10], [11], [12], [13], rectifying [14], [15], giant magnetoresistance (GMR) [16], [17], [18], negative differential resistance (NDR) [19], [20], [21], [22], and so on. This opens the way for a variety of novel electronic applications. Nowadays, with the improvements of science and technology, many experimental techniques, including scanning tunneling microscope [25] or mechanically controllable break junction [26], have been employed to fabricate the molecular junctions. Not only molecules are complex enough to attain dedicated functionalities, but they are identically replicated and cheap to manufacture using chemical synthesis. And electronic devices with specific functions have been able to be constructed at the molecular scale [27]. Molecular spintronics is then a rich field which promises scientific and technological breakthroughs.

However, the experimentation of traditional molecular device has been hindered by technological difficulties, such as the interface instability between the inorganic metallic electrodes and organic molecules, and the oxidation of metallic contacts. The main challenge in molecular electronics is to make a reliable interface between molecules and metal electrodes [28], [29]. Graphene, fortunately, as an atomic monolayer of graphitic carbon, has emerged recently [30]. As a fascinating system for fundamental studies and suitable spintronic material owing to its remarkable physical properties and prospective applications in nanotechnology, it can avoid such interface problems as electrodes [21], [22], [31], [32], [33]. And this ideal, very recently, has been realized in experiment [34]. This suggests that the graphene electrode is stable and feasible in a practical application. According to the basic edge configurations, the graphene nanoribbon (GNR) has two typical types: armchair- and zigzag-edge GNRs (AGNRs and ZGNRs). AGNRs are nonmagnetic semiconductors, but ZGNRs can be antiferromagnetic, ferromagnetic and non-magnetic states, by using external electric fields or chemical modifications [35], [36], [37]. Therefore, ZGNRs are expected to play an important role in future spintronic devices, and it has been considered as a good candidate for molecular device electrodes [21], [22], [31], [32], [33], [34].

On the other hand, the graphene-like polycyclic aromatic hydrocarbon (PAH) molecule and its electron transport have also attracted much attention [38], [39], [40]. PAHs can be regarded as two-dimensional graphite segments composed of all-sp2 carbons and are widely found in the residues of domestic and natural combustion of coal, wood, and other organic materials [39]. Although PAHs are generally known to the chemist as key objects of structural organic chemistry, their particular electronic and self-assembling properties also provide opportunities for novel device fabrications. It was found that the polycyclic anthanthrene core has applicable potential for all-carbon electronics as a building block [41]. And a comonomer attached to anthanthrene unit has only little effect on the electronic property of the polymers [42]. Motivated by the above mentioned works [34], [38], [39], [40], [41], [42], therefore, in this work we propose a PAH-based molecular junction with graphene electrodes, and examine its electron charge and spin transport properties using the first-principles method. The molecule with and without oxidation and two types of contacting manners between anthanthrene and carbon chain are considered, respectively. We demonstrate that this all-carbon nanodevice shows the perfect spin-filtering and -rectifying functionalities and NDR effect. When the molecule is oxidized, interestingly, the current through the junction increases dramatically, and an obvious GMR effect can be reached. As the contacting manner is changed, the NDR effect disappears in the anti-parallel magnetic configuration between the electrodes. We believe that, in the future, this type of all-carbon electronic devices may be realized by removing carbon atoms row by row from a graphene sheet through the controlled energetic electron irradiation inside a transmission electron microscope [43].

The paper is organized as follows: In Sec. 2, we describe the model device and the computational details. In Sec. 3, we present the results and discuss the corresponding physical/chemical mechanisms in terms of the spin-resolved electronic transmission spectrum, the evolution of the frontier molecular orbitals, the local density of states around the Fermi level, and the molecular projected self-consistent Hamiltonian. Finally a summary is given in Sec. 4.

Section snippets

Model and calculation method

The proposed model device is illustrated in Fig. 1. The left and right electrodes are two semi-infinite ZGNRs along the transport z-direction, in which the edge part is designed to have two zigzag edges to enhance the edge magnetism. The central anthanthrene molecule is connected to the electrodes through a pyridine [40], which is tied up to ZGNR electrodes with a five-membered ring [43]. The structure of the junction was optimized before transport calculation. According to the optimization,

Results and discussions

Fig. 2 shows the calculated spin magnetization density isosurfaces at zero bias for M1, M2 and M3 in P and AP spin configurations, respectively, where the red and blue colors denote the spin-up and -down. It can be seen from Fig. 2 that the spin density distribution for M1, M2 and M3 are basically the same in the ZGNR region. It is evident that considerable magnetic moments originate from the edged carbon atoms of ZGNR electrodes, which agree well with previous study [49], [50]. And there is

Summary and conclusion

In summary, we have studied the spin-dependent transport properties for a junction of PAH molecule embedded between two semi-infinite long ZGNR electrodes. The molecule without and with absorptive oxygen atoms in different connecting sites are considered, respectively. And external magnetic fields or FM stripes are applied onto the ZGNRs to initially orient the magnetic alignment of the electrodes for the spin-dependent consideration. By the ab initio calculations based on the DFT combined with

Acknowledgments

This work was supported by the Research Foundation of Hunan Provincial Education Commission (Grant No. 16A124), and the Hunan Provincial Innovation Foundation for Postgraduates (Grant Nos. CX2015B124, CX2016B165).

References (51)

  • Y.S. Liu et al.

    Carbon

    (2016)
  • A. Yamanaka et al.

    Carbon

    (2016)
  • C. Joachim et al.

    Nature

    (2000)
  • S.A. Wolf et al.

    Science

    (2001)
  • Stefano Sanvito

    Chem. Soc. Rev.

    (2011)
  • C. Claude et al.

    Nat. Mater.

    (2007)
  • J.L. Chen et al.

    J. Chem. Phys.

    (2011)
  • H. Hao et al.

    Phys. Rev. Lett.

    (2012)
  • J. Taylor et al.

    Phys. Rev. B

    (2001)
  • H. Hao et al.

    Appl. Phys. Lett.

    (2010)
  • A. Saffarzadeh et al.

    Appl. Phys. Lett.

    (2011)
  • P. Parida et al.

    J. Mater. Chem.

    (2012)
  • A. Smogunov et al.

    Nano Lett.

    (2015)
  • J. Li et al.

    Appl. Phys. Lett.

    (2015)
  • M.G. Zeng et al.

    Appl. Phys. Lett.

    (2010)
  • I.I. Oleynik et al.

    Phys. Rev. Lett.

    (2006)
  • X.Q. Deng et al.

    Appl. Phys. Lett.

    (2009)
  • M.N. Baibich et al.

    Phys. Rev. Lett.

    (1988)
  • Z.H. Xiong et al.

    Nature

    (2004)
  • S. Schmaus et al.

    Nat. Nanotech

    (2011)
  • A. Salomon et al.

    J. Am. Chem. Soc.

    (2004)
  • H. Kim et al.

    J. Phys. Chem. C

    (2011)
  • H.Q. Wan et al.

    J. Phys. Chem. C

    (2012)
  • H.Q. Wan et al.

    J. Chem. Phys.

    (2012)
  • J. Zeng et al.

    Appl. Phys. Lett.

    (2014)
  • Cited by (17)

    • Spin filtering and negative differential resistance in PAQR-ZGNR junctions

      2023, Physica E: Low-Dimensional Systems and Nanostructures
      Citation Excerpt :

      On the other hand, molecular electronics has shown great potential in realizing device miniaturization and large-scale integration since the first proposal of molecule rectifier [19]. Typical functional devices such as spin filtering [20,21], rectification [22–24], giant magnetoresistance (GMR) [23,25] and negative differential resistance (NDR) [22,26] have been predicted as results of strong quantum effects therein. In addition, reversible and light-controlled conductance switching have been observed in molecular devices based on photochromic diarylethene molecules [27].

    • Electronic properties and spintronic applications of r-N-graphyne nanoribbons

      2022, Physica E: Low-Dimensional Systems and Nanostructures
      Citation Excerpt :

      Graphene, carbon atom thin film with hexagonal covalently-bonded structure, has a unique electronic band structure where the carriers behave as massless Dirac fermions [2,3]. Graphene also exhibits novel electronic transport behaviors and has great application potential in spintronic devices [4–7]. However, the nearly zero bandgap nature of graphene also limits its application in microelectronics, which sparks the research interests in the search for two-dimensional materials with finite bandgaps.

    • Functionalized graphene and targeted applications – Highlighting the road from chemistry to applications

      2020, Progress in Materials Science
      Citation Excerpt :

      Actually, repeating cycles of treating the device with the cation followed by removal by EDTA demonstrated a stable chemical switch of conductivity [264]. By means of theoretical investigation, butadienimine [271], (E)- and (Z)- stilbene [272], polycyclic aromatic hydrocarbons [273,274], and 6,11-dioxo-5,6,11,12-tetrahydrobenzo[b]phenazine-1,4,7,10-tetracarbonitrile (DO-THBbPA-TCN) [275] have been examined for their switching properties. Beyond wired nano-patterned graphene, strategies for the interconnection of graphene nanoribbons have been recently developed.

    • Coherent spin transport in a DNA molecule

      2020, Chemical Physics
      Citation Excerpt :

      Furthermore, same as the Dickerson-Drew duplex, it is difficult to estimate the TMR effect even in short DNA molecules such as ds(5′-CGCG-3′) and ds(5′-AATT-3′). By the way, the total energy differences between PA and APA configurations was important for estimating the stability of a molecule-ferromagnetic system [49-51]. The energy differences of a Dickerson-Drew duplex, ds(5′-CGCG-3′), and ds(5′-AATT-3′) were −0.007 eV, −0.14503 eV, and −0.01438 eV, respectively.

    View all citing articles on Scopus
    View full text