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Black phosphorene (BP) have aroused great concern because of its great potential for the application in nanoelectronic devices and high-performance anode materials for alkali metal ion batteries (AIBs). However, the absence of magnetism for an ideal BP limits its wide application in spintronic devices which is one of the important nanoelectronic devices, and its application as a high-performance anode material for AIBs is still to be explored. In this paper, we adopt first-principles calculations to explore the effects of B, C, N, O, F, Al, Si and S atom doping on the magnetic state of monolayer BP and Li or Na atom adsorption and diffusion on the BP. Additionally, the thermal stability of the doped BP systems at room temperature is revealed by the ab initio molecular-dynamics calculations. Our calculated results indicate that O and S doping can make the doped BP become a magnetic semiconductor, C and Si doping makes the doped BP be metallic, and B, N, F and Al doping preserves semiconductor property. Moreover, little structural changes and significant decreases of diffusion barriers in armchair direction and slight increases of diffusion barriers in zigzag direction make B-doped BP beneficial as an anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). It reveals that S-doping is suitable for improving the performance of SIBs rather than LIBs. Interestingly, it is found that magnetic states of O- and S-doped BP disappear when Li or Na atoms adsorb on them, whereas Li or Na adsorption on B- and Al-doped BP induces magnetic states of these systems. The analyses indicate that the distinct electron transfer between the dopant atom, adatom and neighboring P atoms, and specific electron configuration of dopant atoms cause the magnetism of the systems. Our results suggest that selecting appropriate composition to dope can effectively manipulate magnetic state and improve Li/Na adsorption and diffusion on the BP. These results may inspire further theoretical and experimental exploration on doped two-dimensional (2D) materials in spintronics and doped 2D promising anode materials for high-performance metal ion batteries.

Contacts between black phosphorene (BP) and metal electrodes are critical components of BP-based devices and can dramatically affect device performance. In this paper, we adopted first-principles calculations to explore binding energies, electronic structures, spatial potential distribution of monolayer BP–Ni interfaces in surface contact and edge contact types, and used density functional theoretical coupled with nonequilibrium Green’s function method to investigate the electrical transport properties for transport systems of monolayer BP with Ni electrodes. Our calculated results indicate that contact type between monolayer BP and metal Ni electrodes may much affect the transport properties of monolayer BP–Ni devices. Interfacial interaction between Ni and monolayer BP in edge contact type is stronger than that in surface contact type. The potential distributions indicate that edge contact type is more beneficial for reducing contact resistance of monolayer BP–Ni contacts and conducive to improve the performance of BP–Ni electrode device.

Layered transition metal oxide PbPdO2 has great potential application in electronic devices because of its unique electronic structure and large thermoelectric power at room temperature. In this work, strain effect on the electronic structure of PbPdO2 slab with preferred (0 0 2) orientation was systematically investigated using first-principles calculation. The calculated results indicate that PbPdO2 ultrathin slab possesses a small indirect gap while an indirect-direct band gap transition occurs when a moderate 2% compression or tensile strain is applied on the slab. Moreover, this strain induced indirect-direct band gap transition was analyzed in detail using the charge density difference at different point of valence band. The charge transfer and energy barrier with charge polarization resulting from the changes of bond length and angle for Pd-O bonding under the strain, have been accounted for this transition. Remarkablely, for the (0 0 2) preferred orientation PbPdO2 slab, the predicted carrier mobilities of electrons and holes are 11 645.31 and 694.60 cm2 V-1 s-1 along the x-axis direction, 935.05 and 16.05 cm2 V-1 s-1 along the y -axis direction, respectively. These calculated mobilities of electrons along the x-axis direction are larger than those for 2D MoS2 (~400 cm2 V-1 s-1), and being comparable to those for InSe (103 cm2 V-1 s-1) and black phosphorene (103-104 cm2 V-1 s-1). It is strong suggested that the (0 0 2) orientated PbPdO2 slab with high mobility should be an ideal candidate material for the application of electronics devices.

Magnetic doping in topological insulator Sbalt;subagt;2alt;/subagt;Tealt;subagt;3alt;/subagt; can produce very novel physical phenomena such as quantum anomalous Hall effect (QAHE). However, experimental observations of QAHE in the magnetic atoms doped Sbalt;subagt;2alt;/subagt;Tealt;subagt;3alt;/subagt; have encountered significant challenges due to the complexity of the electronic structure and the relatively small band gap. Generally, mechanical strain can effectively modulate the band structure, thus we theoretically investigate the electronic structures of Cr-doped Sbalt;subagt;2alt;/subagt;Tealt;subagt;3alt;/subagt; under mechanical strain using first-principles calculations within density functional theory (DFT). The band gap of Cr-doped Sbalt;subagt;2alt;/subagt;Tealt;subagt;3alt;/subagt; is 0.031eV. When the compressive strain η becomes as -2%, the band gap will be further enlarged to 0.045eV, which is 45% larger than that of the unstrained material. However, as the compressive strain η exceed -2%, strong hybridization between Cr and Te atoms will cause the overlap of bands, which leads to the closure of band gap. In addition, when tensile strain are applied to Cr-doped Sbalt;subagt;2alt;/subagt;Tealt;subagt;3alt;/subagt;, the decrease in the spacing between quintuple layers (QLs) can enhance the coupling between Te and Sb atoms, which can also result in the closing of the band gap. Finally, we used HSE06 to calculated the band gaps. The band gaps may be underestimated, but HSE06 and GGA have the same band structures evolution tendency under mechanical strain. Our calculated results provide a guideline for the modulation of band structure by mechanical strain, which pave the way for the observation of QAHE in Cr-doped Sbalt;subagt;2alt;/subagt;Tealt;subagt;3alt;/subagt;.

The angular dependence of specific precession modes of an Ni nanowire array in the magnetization process was thoroughly investigated by ferromagnetic resonance. Compared with the uniform precession mode in near-saturated states, additional resonance was observed at low applied fields when the field orientation diverged from the wire axis. The origin of such a low-field resonance is discussed in detail in the transverse magnetization case. The particular resonances were considered from the spin precession in remanent longitudinal domains in the unsaturated states of the nanowires, which gave strong experimental evidence of a nucleation mode in the magnetization process of the nanowire array.

The spin-resolved electronic structure of AlN doped with 6.25% Cu has been studied by first-principles calculations based on spin density functional theory. A single substitutional Cu impurity and its nearest neighbouring N atoms have a spin polarized state with a global magnetization of 2.00 μB. Band structures show a half metallic behaviour of Cu-doped AlN. Cu-doped AlN has a ferromagnetic ground state which can be explained by a p–d hybridization mechanism. These results indicate that Cu-doped AlN shows promise as a dilute magnetic semiconductor (DMS). This study give new clues to the fabrication of DMSs.