Recently, borophene has attracted extensive interest as the wonder material, showing that line defects (LDs) occur widely at the interface between $$\nu _{1/5}$$ ν 1 / 5 and $$\nu _{1/6}$$ ν 1 / 6 boron sheets. Here, we study theoretically the electron transport through two-terminal disordered borophene nanoribbons (BNRs) with random distribution of LDs. Our results indicate that LDs strongly affect the electron transport properties of BNRs. Both $$\nu _{1/5}$$ ν 1 / 5 and $$\nu _{1/6}$$ ν 1 / 6 BNRs exhibit metallic behavior without any LD, in agreement with experiments. While in the presence of LDs, the overall electron transport ability is dramatically decreased, but some resonant peaks of conductance quantum are found in the transmission spectrum of any disordered BNR with arbitrary arrangement of LDs. These disordered BNRs exhibit metal-insulator transition with tunable transmission gap in the insulating regime. Furthermore, two evolution phenomena of resonant peaks are revealed for disordered BNRs with different widths. These results may help for understanding structure-property relationships and designing LD-based nanodevices.

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DNA electronics has reattracted great interest in recent years and showed a number of fascinating phenomena. Here, we present a theoretical study of electron transport through a two-terminal circular DNA junction under a perpendicular magnetic field. Our results indicate that this circular DNA exhibits Aharonov–Bohm-like effects and a semiconductor–insulator–semiconductor transition by tuning this magnetic field, with the transmission spectrum nearly oscillating periodically. Interestingly, Fano resonances appear around integer multiples of the magnetic flux quantum accompanied by several vortices of local currents. Moreover, the circular DNA behaves as a nanoscale switch, and this switching effect is robust and could be improved for longer molecular length and weaker molecule–electrode coupling, with the on/off ratio exceeding 104 for long circular DNA. These results may help for designing novel circular DNA-based molecular devices.

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