Co-doped BaFe_(2)As_(2) Josephson junction fabricated with a focused helium ion beam

Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices,therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance.In this work,we have successfully fabricated Josephson junctions from Co-doped BaFe_(2)As_(2)thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam(FHIB).The electrical transport properties were investigated for junctions fabricated with various He^(+)irradiation doses.The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K,and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He^(+)irradiation.Significant J_c suppression by more than two orders of magnitude can be achieved by increasing the He^(+)irradiation dose,which is advantageous for the realization of low noise ion pnictide thin film devices.Clear Shapiro steps are observed under 10 GHz microwave irradiation.The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe_(2)As_(2)Josephson junction with high reproducibility using the FHIB technique,laying the foundation for future investigating the mechanism of iron-based superconductors,and also the further implementation in various superconducting electronic devices.

High-Temperature Superconducting YBa_(2)Cu_(3)O_(7-δ)Josephson Junction Fabricated with a Focused Helium Ion Beam

As a newly developed method for fabricating Josephson junctions,a focused helium ion beam has the advantage of producing reliable and reproducible junctions.We fabricated Josephson junctions with a focused helium ion beam on our 50 nm YBa_(2)Cu_(3)O_(7-δ)(YBCO)thin films.We focused on the junction with irradiation doses ranging from 100 to 300 ions/nm and demonstrated that the junction barrier can be modulated by the ion dose and that within this dose range,the junctions behave like superconductor–normal conductor–superconductor junctions.The measurements of the I–V characteristics,Fraunhofer diffraction pattern,and Shapiro steps of the junctions clearly show AC and DC Josephson effects.Our findings demonstrate high reproducibility of junction fabrication using a focused helium ion beam and suggest that commercial devices based on this nanotechnology could operate at liquid nitrogen temperatures.

Metformin escape in prostate cancer by activating the PTGR1 transcriptional program through a novel super-enhancer

The therapeutic efficacy of metformin in prostate cancer(PCa)appears uncertain based on various clinical trials.Metformin treatment failure may be attributed to the high frequency of transcriptional dysregulation,which leads to drug resistance.However,the underlying mechanism is still unclear.In this study,we found evidences that metformin resistance in PCa cells may be linked to cell cycle reactivation.Super-enhancers(SEs),crucial regulatory elements,have been shown to be associated with drug resistance in various cancers.Our analysis of SEs in metformin-resistant(MetR)PCa cells revealed a correlation with Prostaglandin Reductase 1(PTGR1)expression,which was identified as significantly increased in a cluster of cells with metformin resistance through single-cell transcriptome sequencing.Our functional experiments showed that PTGR1 overexpression accelerated cell cycle progression by promoting progression from the G0/G1 to the S and G2/M phases,resulting in reduced sensitivity to metformin.Additionally,we identified key transcription factors that significantly increase PTGR1 expression,such as SRF and RUNX3,providing potential new targets to address metformin resistance in PCa.In conclusion,our study sheds new light on the cellular mechanism underlying metformin resistance and the regulation of the SE-TFs-PTGR1 axis,offering potential avenues to enhance metformin’s therapeutic efficacy in PCa.