•Spin-polarized transport properties of Fe-oligoporphyrin dimer (Fe-P2TA) are studied.•High-efficiency magnetoresistance, spin filtering, and low-bias negative differential resistance effects are observed.•The system is a potential candidate for designing multifunctional spintronic devices.By applying the density functional theory and the nonequilibrium Green’s function formalism, we investigate the spin-polarized transport properties of a Fe-oligoporphyrin dimer (Fe-P2TA) sandwiched between two armchair single-walled carbon nanotube electrodes. The results show that the system can present high-efficiency magnetoresistance, spin-filtering, and low-bias negative differential resistance effects with the help of magnetic field modulation. The above results are explained by the evolution of the spin-polarized transmission spectra and the molecular projected self-consistent Hamiltonian eigenstates with applied bias. Therefore, the system provides the possibilities for a multifunctional molecular spintronic device design.We investigate the spin-polarized transport properties of a Fe-P2TA molecule sandwiched between two carbon nanotube electrodes. The results show that the system can present high-efficiency magnetoresistance, spin-filtering, and low-bias negative differential resistance effects with the help of magnetic field modulation.

Based on first-principles density functional theory combined with the nonequilibrium Green's function method, we have investigated the spin-dependent transport properties of a pyrene–zigzag graphene nanoribbon (ZGNR) system. The results show that this system can exhibit high-performance spin filtering, spin rectifying, giant magnetoresistance and negative differential resistance effects, by tuning the magnetization configuration of ZGNR electrodes. By analyzing the spin-resolved transmission spectrum, the local density of states, the transmission pathways, the band structure and symmetry of ZGNR electrodes, as well as the spatial distribution of molecular orbitals within the bias window, we elucidate the mechanism for these intriguing properties. Our results suggest that the pyrene–ZGNR system is a potential candidate for developing high-performance multifunctional spintronic devices.

Based on spin-polarized first-principles density functional theory combined with nonequilibrium Green's function method, the thermal spin transport properties of a nitroxide radical-based molecule sandwiched between two Au electrodes are investigated. The results show that opposite spin currents can be induced by applying a temperature difference, rather than bias voltage, between two electrodes. Moreover, a pure spin current and a completely spin-polarized current can be realized by tuning the transverse gate voltage. These results indicate that the nitroxide radical-based molecule is a potential material for spin caloritronic and spintronic applications.

•Magnetic transport properties of DBTAA and transition metal-DBTAA with ZGNR electrodes are investigated.•DBTAA system can exhibit giant magnetoresistance, spin-filtering and spin-polarized current rectifying effects.•Introducing of TM atoms has obvious effects on these spin-related effects.Based on the density functional theory combined with the nonequilibrium Green’s function formalism, the magnetic transport properties of dibenzotetraaza[14]annulene (DBTAA) and transition metal (TM)-DBTAA (TM = Fe and Co) sandwiched between two ferromagnetic zigzag-edge graphene nanoribbon electrodes are investigated. The results show that giant magnetoresistance, spin-filtering and spin-polarized current rectifying effects can be realized simultaneously in the DBTAA system by modulating the external magnetic field. Introducing of TM atoms has obvious effects on these spin-related effects. The mechanisms of these intriguing phenomena are proposed and these phenomena would be instructive in the design of high-performance magnetic nanodevices.We investigate systematically the magnetic transport properties of DBTAA and transition metal (TM)-DBTAA (TM = Fe and Co) sandwiched between two ZGNR electrodes. The results show that giant magnetoresistance, spin-filtering and spin-polarized current rectifying effects can be realized simultaneously in the DBTAA system. And introducing of TM atoms has obvious effects on these effects.

Based on spin-polarized first-principles density functional theory in conjunction with the nonequilibrium Green's function method, the spin transport properties of transition metal (TM)–dibenzotetraaza[14]annulene (DBTAA) complexes (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) sandwiched between two Au electrodes are investigated. The results show that Fe– and Co–DBTAA can display perfect spin filtering behavior in a wide bias voltage region. Moreover, it is found that the connected position of anchoring groups on the complexes affect significantly the spin filtering efficiency. The observed spin filtering behavior is explained by the spin-resolved transmission spectrum and molecular projected self-consistent Hamiltonian state analyses.

By using the nonequilibrium Green's function formalism in combination with the density functional theory, we have investigated the spin transport properties of a 4H-TAHDI-based multifunctional spintronic device constructed by contacting a 4H-TAHDI molecule with two ferromagnetic zigzag-edge graphene nanoribbon electrodes. The results show that perfect giant magnetoresistance, spin-filtering, bipolar spin-rectifying, and negative differential resistance effects can be realized simultaneously. The mechanisms were proposed for these interesting phenomena. Our results demonstrate that this system holds promise in the design of a high-performance multifunctional single-molecule spintronic device.

•Transport properties of a single-molecule magnet Mn(dmit)2 with two ferromagnetic ZGNR electrodes are studied.•The system presents large rectifying, giant magnetoresistance, spin-filtering and negative differential resistance effects.•An improved switching effect can also be realized by changing the orientation between planes of two dmit ligands.By applying the density functional theory and the nonequilibrium Green’s function formalism, we investigate the spin transport properties of a single-molecule magnet Mn(dmit)2 sandwiched between two ferromagnetic zigzag-edge graphene nanoribbon electrodes. The results show that the system can present large rectifying, giant magnetoresistance, spin-filtering and negative differential resistance effects with the help of magnetic field modulation. Moreover, an improved switching effect can also be realized by changing the orientation between planes of two dmit ligands. Therefore, the system will provide the possibilities for a multifunctional molecular device design.We investigate the spin transport properties of a single-molecule magnet Mn(dmit)2 sandwiched between two ferromagnetic zigzag-edge graphene nanoribbon electrodes. The results show that the system can present large rectifying, giant magnetoresistance, spin-filtering, negative differential resistance and switching effects.

By using a combined method of density functional theory and nonequilibrium Green’s function formalism, we investigate the electronic transport properties of a gated C60 dimer molecule sandwiched between two gold electrodes. The results show that the gate voltage can strongly affect the electronic transport properties of the C60 dimer and change it from semiconducting to metallic. Negative differential resistance behaviors are obtained in such systems and can be modulated to occur at much lower bias by the gate voltage. The low bias negative differential resistance is analyzed from the calculated transmission spectra, projected density of states and the spatial distribution of molecular projected self-consistent Hamiltonian orbitals along with the voltage drop. These results provide a theoretical support to the design of low bias negative differential resistance molecular device by using the modulation of gate voltage.Graphical abstractWe present a systematic study of electronic transport properties of a gated C60 dimer molecule sandwiched between two gold electrodes.Highlights► Effect of gate voltage on electronic transport properties of the C60 dimer is studied. ► Gate voltage can change the system from semiconducting to metallic. ► Negative differential resistance behavior can be modulated to occur at much lower bias by the gate voltage.

•Spin-polarized transport properties of an endohedral Fe@C60 dimer are investigated.•Direction of the magnetic moments of two Fe atoms can be controlled by applying a magnetic field.•Magnetoresistance, spin filtering and negative differential resistance effects can be observed.Based on non-equilibrium Green's method and density functional theory, the spin-polarized transport properties of an endohedral Fe@C60 dimer-based spintronic device are investigated. The direction of the magnetic moments of the two Fe atoms can be controlled by applying a magnetic field. The interesting magnetoresistance, spin filtering and negative differential resistance effects can be observed in this device. These phenomena are explained by the evolution of spin-dependent transmission spectra and projected density of states with the increase in bias, as well as the voltage drop distributions.

Using first-principles density functional theory and real-space non-equilibrium Green′s function formalism for quantum transport calculation, we investigate all-carbon mechanically controlled molecular devices which consists of only two (5,5) armchair and two (6,0) zigzag single-walled carbon nanotubes (SWCNTs) opposing one another. Our results show that the chirality of SWCNTs and the electrode–electrode distance have crucial effects on the electronic transport properties of such systems. When the right SWCNT electrode is mechanically pushed forward along its axial direction, obvious negative differential resistance behaviors are observed in the zigzag system, but not in the armchair case.Graphical abstractTransport properties of SWCNT-based molecular devices are investigated. NDR behaviors are observed in the zigzag system at appropriate electrode–electrode distance, but not in the armchair case.Highlights► Electronic transport properties of all-carbon mechanically controlled molecular devices based on SWCNT are studied. ► Chirality of SWCNTs and electrode–electrode distance have crucial effects on the electronic transport properties. ► Obvious NDR behaviors are observed in the zigzag system at appropriate electrode–electrode distance.

By applying nonequilibrium Green’s function formalism in combination with density functional theory, we have investigated the electronic transport properties of armchair graphene nanoribbon devices with periodic nitrogen-doping. Giant negative differential resistance behaviors with peak-to-valley ratio up to the order of 105 can be obtained in the mV bias regime by tuning the position and the concentration of the dopants. The negative differential resistance behavior is understood in terms of the evolution of the transmission spectrum and band structures with applied bias combined with the symmetry analyses of the Bloch wave functions of the corresponding subbands.Graphical abstractWe present a systematic study of the electronic transport properties of armchair graphene nanoribbon devices with periodic nitrogen-doping. Giant negative differential resistance behaviors with peak-to-valley ratio up to the order of 105 can be obtained in the mV bias regime by tuning the position and the concentration of the dopants.Highlights► Electronic transport properties of armchair graphene nanoribbon devices with periodic nitrogen-doping are studied. ► Transport properties are strongly dependent on the position and the concentration of the dopants. ► Giant NDR behaviors with peak-to-valley up to the order of 105 can be obtained in the mV bias regime.

Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of heteronanotubes by joining a zigzag (6,0) carbon nanotube and a zigzag (6,0) boron nitride nanotube with different atomic compositions and joint configurations. Our results show that the atomic composition and joint configuration affect strongly the electronic transport properties. Obvious negative differential resistance behavior and large rectifying behavior are obtained in the heterostructure with certain composition and joint configuration. Moreover, tube length and tube radius can affect strongly the observed NDR and rectifying behaviors. The observed negative differential resistance and rectifying behaviors are explained in terms of the evolution of the transmission spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analysis.Highlights► Transport properties of heteronanotubes based on zigzag C- and BN-nanotubes are studied. ► Atomic composition and joint configuration affect strongly the transport properties. ► Obvious NDR and large rectifying behaviors are observed under certain conditions.

Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of (8,0), (9,0) and (13,0) zigzag single-walled carbon nanotube junctions with one undoped and one nitrogen-doped zigzag carbon nanotube electrode. Our results show that the transport properties are strongly dependent on the magnitude of energy gap of carbon nanotube. Large rectifying behavior can be obtained in the junction with large energy gap. The observed rectifying behavior are explained in terms of the evolution of the transmission spectra and energy band structures with applied bias voltage combined with molecular projected self-consistent Hamiltonian eigenstates analysis.Highlights► Transport properties of nitrogen-doped zigzag single-walled carbon nanotubes are studied. ► Transport properties strongly depend on the magnitude of energy gap of carbon nanotube. ► Large rectifying behavior occurs in the nitrogen-doped carbon nanotube with large energy gap.

By applying non-equilibrium Green’s function in combination with density functional theory, we investigated the electronic transport properties of capped-carbon-nanotube-based molecular junctions with multiple N and B dopants. The results show that the electronic transport properties are strongly dependent on the numbers and positions of N and B dopants. Best rectifying behavior is observed in the case with one N and one B dopants, and it is deteriorated strongly with the increasing dopants. The rectifying direction is even reversed with the change of doping positions. Moreover, obvious negative differential resistance behavior at very low bias is observed in some doping cases.

We investigate using the Landauer formalism, which combines both the non-equilibrium Green’s function and density functional theory, the effects of separation and orientation between two electrodes of boron-doped capped-carbon-nanotube-based molecular junctions on negative differential resistance. The results show that this negative differential resistance behavior is strongly dependent on the separation and orientation between the two electrodes. A gap width of 0.35 nm and maximal symmetry achieves the best negative differential resistance behavior.

By applying the nonequilibrium Green function formalism combined with density functional theory, we have investigated the electronic transport properties of the C60 dimer and its endohedral complex Li@C60 dimer. Our results show that the doping of Li atoms significantly changes the transport properties of the C60 dimer. Negative differential resistance is found in such systems. Especially, the doping of Li atoms can lead to a much larger negative differential resistance at much lower bias, and it is quite evident from the plot of differential conductance versus bias. The negative differential resistance behavior is understood in terms of the evolution of the transmission spectrum and projected density of states spectrum with applied bias combined with molecular projected self-consistent Hamiltonian states analyses.

Using first-principles density functional theory, we have investigated the catalytic oxidation of CO on Fe-embedded hexagonal boron nitride (h-BN) sheet. Fe atom can be constrained at a boron vacancy site of h-BN sheet with a high diffusion barrier (3.70 eV), and effectively activate the adsorbed O2 molecule. The reactions between the adsorbed O2 with CO via both Langmuir–Hinshelwood and Eley–Rideal mechanisms were comparably studied. The reaction proceeds via the more favorable Eley–Rideal mechanism with a two-step route (CO + O2 → CO2 + O and CO + O → CO2). The energy barriers are 0.56 and 0.61 eV, respectively.Graphical abstractWe have investigated theoretically the catalytic oxidation of CO on Fe-embedded h-BN sheet. The reaction proceeds rapidly via the Eley–Rideal mechanism due to the low energy barriers.Highlights► CO catalytic oxidation on Fe-embedded h-BN sheet is studied for the first time. ► Fe can be constrained at a B-vacancy, and effectively activates the O2 molecule. ► The oxidation could proceed rapidly because of the low energy barriers.

Using first-principles density functional theory and the non-equilibrium Green’s function formalism, we have studied the electronic transport properties of the dumbbell-like fullerene dimer C131-based molecular junction. Our results show that the current–voltage curve displays an obvious negative differential resistance phenomenon in a certain bias voltage range. The negative differential resistance behavior can be understood in terms of the evolution of the transmission spectrum and the projected density of states with applied bias voltage. The present findings could be helpful for the application of the C131 molecule in the field of single molecular devices or nanometer electronics.Highlights► The electronic transport properties of the C131 molecule are studied for the first time. ► The current–voltage curve exhibits a highly unsymmetrical feature and semiconducting behavior. ► An obvious negative differential resistance phenomenon is observed.

Using the Landauer formalism that combines both the non-equilibrium Green’s function and first-principles density functional theory, the electron transport properties of a one-dimensional molecular junction based on capped carbon nanotubes with boron doping at various sites are investigated. The results show that the electron transport properties are strongly dependent on the boron-doping site. Negative differential resistance behavior can be observed when boron-atom dopants are present in the tip region.

Using the Landauer formalism that combines both the non-equilibrium Green’s function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.

Using first-principles density functional theory and non-equilibrium Green's function formalism for quantum transport calculation, we have investigated the electronic transport properties of (8,0), (9,0) and (13,0) zigzag single-walled carbon nanotube junctions with one undoped and one nitrogen-doped zigzag carbon nanotube electrode. Our results show that the transport properties are strongly dependent on the magnitude of energy gap of carbon nanotube. Large rectifying behavior can be obtained in the junction with large energy gap. The observed rectifying behavior are explained in terms of the evolution of the transmission spectra and energy band structures with applied bias voltage combined with molecular projected self-consistent Hamiltonian eigenstates analysis.Highlights► Transport properties of nitrogen-doped zigzag single-walled carbon nanotubes are studied. ► Transport properties strongly depend on the magnitude of energy gap of carbon nanotube. ► Large rectifying behavior occurs in the nitrogen-doped carbon nanotube with large energy gap.

Based on the density functional theory in conjunction with the non-equilibrium Green's function formalism, we explore the effect of transition metal (Mn, Fe, Co, Ni) ions on the magnetic transport properties of a new synthesized colorimetric chemosensor L. The calculated results show that only Mn-L can present high-efficiency spin filtering effect, even at room temperature. The underlying mechanism is explained by the spin-resolved electron occupation number, transmission spectra, molecular projected self-consistent Hamiltonian orbitals and their spatial distribution.

By using the nonequilibrium Green's function formalism in combination with the density functional theory, we have investigated the spin transport properties of a 4H-TAHDI-based multifunctional spintronic device constructed by contacting a 4H-TAHDI molecule with two ferromagnetic zigzag-edge graphene nanoribbon electrodes. The results show that perfect giant magnetoresistance, spin-filtering, bipolar spin-rectifying, and negative differential resistance effects can be realized simultaneously. The mechanisms were proposed for these interesting phenomena. Our results demonstrate that this system holds promise in the design of a high-performance multifunctional single-molecule spintronic device.