Qiu-Hua Wu

A first-principles study of the spin transport properties of a 4H-TAHDI-based multifunctional spintronic device with graphene nanoribbon electrodes

By using the nonequilibrium Greens 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.

Spin transport of dibenzotetraaza[14]annulene complexes with first row transition metals

Based on spin-polarized first-principles density functional theory in conjunction with the nonequilibrium Greens 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.

Spin-dependent transport properties in a pyrene–graphene nanoribbon device

Based on first-principles density functional theory combined with the nonequilibrium Greens 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.

Thermal spin transport of a nitroxide radical-based molecule

Based on spin-polarized first-principles density functional theory combined with nonequilibrium Greens 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.

Spin Caloritronic Transport of 1,3,5-Triphenylverdazyl Radical

We investigate theoretically the spin caloritronic transport properties of a stable 1,3,5-triphenylverdazyl (TPV) radical sandwiched between Au electrodes through different connection fashions. Obvious spin Seebeck effect can be observed in the para-connection fashion. Furthermore, a pure spin current and a completely spin-polarized current can be realized by tuning the gate voltage. Furthermore, a 100% spin polarization without the need of gate voltage can be obtained in the meta-connection fashion. These results demonstrate that TPV radical is a promising material for spin caloritronic and spintronic applications.