摘要：
Using nonequilibrium Green's function combined with density functional theory, we investigate the transport properties of a single perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecular device before and after adsorbing single heavy metal atoms Ni, Pd, Cd, Cu, Zn, and Ag. We find that the adsorption of a single Ni or Pd atom has a slight modulation on the I–V characteristic of the junction. However, the adsorptions of a single Cd, Cu, Zn, and Ag atom can shift the transmission spectra of the junctions obviously leading to the large decrease in the conductance. The results of this study have certain guiding significance for the practical preparation of heavy metal atom sensors for organic molecules in the future.
摘要：
Using ab initio quantum-transport simulations, we studied the intrinsic transfer characteristics and benchmarks of the ballistic performance of 5.1 nm double-gated Schottky-barrier field effect transistors (SBFETs) consisting of in-plane (IP) heterojunctions of metallic-phase (1T or 1T') MTe2 (M = Ti, Zr, Hf, Cr, Mo, W) and semiconducting-phase (2H) WSe2, WTe2 and Janus WSeTe. The 2H-phase Janus WSeTe is a semiconductor with an indirect bandgap (1.26 eV), which is less than the bandgap of 2H-phase WSe2 (1.64 eV) and is greater than the bandgap of 2H-phase WTe2 (1.02 eV). The band alignments show that all IP 1T/2H contacts are Schottky-barrier contacts with the Fermi levels of 1T or 1T' MTe2 (M = Ti, Zr, Hf, Cr, Mo, W) located within the bandgaps of 2H WSe2, WTe2 and Janus WSeTe. Although double-gated IP WSe2-SBFETs can satisfy the OFF current requirement, their ON currents all fall below the requirements of the high performance transistor outlined by the ITRS (International Technology Roadmap for Semiconductors, 2013 version) for the production year 2028. Double-gated IP WTe2-SBFETs cannot overcome the short channel effect leading to minimum drain currents all beyond the OFF current requirement of ITRS (2013 version) for the production year 2028. Fortunately, double-gated IP WSeTe-SBFETs with 1T MoTe2 or 1T' WTe2 electrodes can overcome the short channel effect and satisfy the requirements of the high-performance transistor outlined by the ITRS (2013 version) for the production year 2028.
期刊：
PHYSICAL CHEMISTRY CHEMICAL PHYSICS,2020年22(7):4080-4085 ISSN：1463-9076
通讯作者：
Qiu, Ming
作者机构：
[Han, Lingyun; Xia, Ying; Shuai, Ling; Wang, Yiping; Ma, Yao; Qiu, Ming] Cent China Normal Univ, Inst Nanosci & Nanotechnol, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.;[Zhang, Zhenhua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410114, Peoples R China.;[Leung, Michael K. H.] City Univ Hong Kong, Abil R&D Energy Res Ctr, Sch Energy & Environm, Hong Kong, Peoples R China.
通讯机构：
[Qiu, Ming] C;Cent China Normal Univ, Inst Nanosci & Nanotechnol, Coll Phys Sci & Technol, Wuhan 430079, Peoples R China.
摘要：
Many organic molecules have unique magnetic properties and can potentially serve as excellent molecular spin devices, which is worth exploring deeply. Here, the spin transport properties of Mn, Fe, Co and Cu porphyrin dimer devices are investigated based on the first principles method. The spin filtering efficiencies of these molecular devices are maintained at 100% within certain applied voltage ranges and magnetoresistance ratios are higher than 10(8)% which increase as the voltage increases. To explain the excellent spin-filtering and giant magnetoresistance effects, analysis of spin electron densities and transmission spectra indicates that magnetic properties are mainly contributed by the metal atoms and their neighbouring N atoms. From the transmission pathway studies, spin electrons come mainly through the pi-conjugated structure of the metal porphyrin ring. Interestingly, in the Cu porphyrin dimer device, magnetic moments of the Cu-N structure in the Cu porphyrin dimer device show spin behaviors different from those of Mn, Fe and Co porphyrin dimer devices.
作者机构：
[Sun, Lin; Li, Mo] Cent S Univ, Sch Phys & Elect, Changsha 410083, Hunan, Peoples R China.;[Zhang, Zhen Hua; Sun, Lin] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410114, Hunan, Peoples R China.;[Sun, Lin] Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monitor, Changsha 410114, Hunan, Peoples R China.;[Wang, Hao] Shenzhen Univ, Coll Mechatron & Control Engn, Guangdong Prov Key Lab Micro Nano Optomechatron E, Shenzhen 518060, Peoples R China.;[Li, Mo] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
通讯机构：
[Li, Mo] C;[Wang, Hao] S;[Li, Mo] G;Cent S Univ, Sch Phys & Elect, Changsha 410083, Hunan, Peoples R China.;Shenzhen Univ, Coll Mechatron & Control Engn, Guangdong Prov Key Lab Micro Nano Optomechatron E, Shenzhen 518060, Peoples R China.
摘要：
Using first-principles calculation based on density-functional theory, the electronic properties of monolayer black phosphorus nanoribbons (PNRs) with and without punched nanoholes (PNRPNHs) and their mechanical stability are studied systematically. We show that while the perfect PNRs and the PNRPNHs have similar properties as semiconductors in both armchair-edge PNR and zigzag-edge PNR structures, the nanoholes can lead to changes in the electronic structure: the zigzag-edge PNRPNH undergoes a direct-to-indirect bandgap transition while the armchair-edge PNRPNH still retains a direct bandgap but with a significant increase in the bandgap as compared to the perfect PNRs. We found also that nanoholes have little influence on the structural stability of PNRs; but the applied external transverse electric field and strain can be more effective in modulating the bandgaps in the PNRPNHs. These new findings show that PNRs are a promising candidate for future nanoelectronic and optoelectronic applications.
期刊：
JOURNAL OF PHYSICS-CONDENSED MATTER,2018年30(44):445802 ISSN：0953-8984
通讯作者：
Zhang, Z. H.
作者机构：
[Yuan, P. F.; Fan, Z. Q.; Zhang, Z. H.; Hu, R.] Changsha Univ Sci & Technol, Inst Nanomat & Nanostruct, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Zhang, Z. H.] C;Changsha Univ Sci & Technol, Inst Nanomat & Nanostruct, Changsha 410114, Hunan, Peoples R China.
关键词：
phagraphene nanoribbon;half-metal;magnetic phase transition;functional group;electric field
摘要：
Magnetic nanomaterials with the desirable nature are the basis for developing future spintronic devices, and research for them is of fundamental interest. Here, we explore the realization of half-metallicity and magnetic phase transition for phagraphene nanoribbons in virtue of functional groups (OH and CN) with different coverage fractions and external electric fields. The first-principles calculations show that a single-edge CN functionalization only makes a intrinsic spin-degenerate semiconducting ribbon converted to a quasi-metal or metal, while a single-edge OH modification leads to an occurrence of the half-semiconducting nature regardless of the coverage fraction of groups. Interestingly, the half-metal behavior for the CN and OH double-edge modified ribbons can be achieved either in the zero-electric-field intrinsic state for most of functionalized systems or at a very low electric field, 0.1 V angstrom(-1). More importantly, the observed critical electric field for the transition from ferromagnetic to nonmagnetic phase is lowered significantly almost for all systems, this benefits to design a low electric-field-controlling magnetic switch which can reversibly work between both magnetic and nonmagnetic states. The calculated Gibbs free energy confirms that the group-modified ribbons generally hold a more favorable energy stability in most of the cases, facilitating likely experimental realization.
摘要：
Exploring half-metallic nanostructures is a crucial solution for developing high-performance spintronic devices. Black phosphorene is an emerging two-dimensional material possessing strong anisotropic band structure and high mobility. Based on the first principles calculations, we investigated the electronic and magnetic properties of zigzag phosphorene nanoribbons (ZPNRs) with three different functionalization groups (OH/CN, OH/NO2, NH2/NO2) at the edges. We find that the interplay between edge functionalization and edge oxidation can induce the half metal phase in the ZPNRs, and the half metal phase can be controlled by the external transverse in-plane electric field and the proportion of the functional groups and edge oxidation. The results may pave a new way to construst nanoscale spintronic devices based on black phosphorene nanoribbons.
摘要：
One-dimensional phosphorus nanotubes (PNTs) are important derivatives of phosphorene. Herein, the magneto-electronic properties for PNTs doped with low-concentration transition metals (TM) (Fe, Co, and Ni) both in their inner and outer layers were investigated in detail. TM-PNTs are very stable with high structural integrity and versatile magnetic properties. In particular, some important magnetic properties such as half-metallic and dilute magnetic semiconducting behaviors can be observed, which are the basis of the application of TM-PNTs in spintronics. Furthermore, the electric field can induce magnetic phase transitions and demagnetization can occur under a very low electric field due to Co-doping in the outer layer of the PNTs. This interesting feature is very attractive for constructing electric-field-controllable magnetic/nonmagnetic switch devices that are operated in two possible states.
作者：
Hu, R.;Fan, Z. Q.;Fu, C. H.;Nie, L. Y.;Huang, W. R.;...
期刊：
Carbon,2018年126:93-104 ISSN：0008-6223
通讯作者：
Zhang, Z. H.
作者机构：
[Fan, Z. Q.; Huang, W. R.; Fu, C. H.; Zhang, Z. H.; Hu, R.; Nie, L. Y.] Changsha Univ Sci & Technol, Inst Nanomat & Nanostruct, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Zhang, Z. H.] C;Changsha Univ Sci & Technol, Inst Nanomat & Nanostruct, Changsha 410114, Hunan, Peoples R China.
摘要：
Based on the first-principles method, the magnetic properties for zigzag-edge graphene nanoribbon (ZGNR) junctions are investigated. The results show the system had the ferromagnetic or antiferro-magnetic ground state depending on the connection sites between ZGNR electrodes and the central ZGNR. The junction displays a metallic behavior when the central ZGNR is connected at the middle site of electrodes with a ferromagnetic state, but shows obvious spin semiconductor feature when the connection site is shifted to the edge of the ZGNR. For the antiferromagnetic states, all models show a semiconductor behavior, which originates from the spin-degenerate edge states. While for the anti-parallel spin configuration, the spin density of the central ribbon is affected by connection sites, and it shows weaker little by little with the central ribbon moving from bottom to the middle site, which is different obviously from ferromagnetic or antiferromagnetic state. When one edge state of the central ZGNR is broken, bipolar spin semiconductor features can be obtained with different band gaps at suitable connection sites. (C) 2016 Elsevier B.V. All rights reserved.
期刊：
PHYSICAL CHEMISTRY CHEMICAL PHYSICS,2017年19(6):4469-4477 ISSN：1463-9076
通讯作者：
Zhang, Z. H.
作者机构：
[Yuan, P. F.; Fan, Z. Q.; Zhang, Z. H.; Liu, J.] Changsha Univ Sci & Technol, Inst Nanomat & Nanostruct, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Zhang, Z. H.] C;Changsha Univ Sci & Technol, Inst Nanomat & Nanostruct, Changsha 410114, Hunan, Peoples R China.
摘要：
The structural and magneto-electronic properties and electric field-mediated effects for zigzag boron nitride nanoribbons (ZBNNRs) terminated with typical transition metal (TM) atoms (TM-ZBNNRs) are investigated systematically. Our work demonstrates that ZBNNRs form strong bonds with all studied termination atoms. The strong interactions and large orbital hybridizations of TM atoms to the ribbon make the magnetic anisotropy enhanced significantly, favorably to stabilize magnetism. The spin-split features for such hybridized structures can occur in most of the magnetic configurations, leading to a large magnetic moment. Higher spin polarization can be found in the ferromagnetic (FM) state. In particular, spin polarization exceeding 90% at the Fermi level can be achieved for Fe-ZBNNRs when an in-plane transverse electric field is applied. These results might be of interest from the prospects of both fundamental science and its potential applications.
