By partially doping Pb to effectively suppress the superstructure in single-layered cuprate Bi_2Sr_2CuO_(6+δ)(Pb-Bi2201) and annealing them in vacuum or in high pressure oxygen atmosphere, a series of high quality Pb...By partially doping Pb to effectively suppress the superstructure in single-layered cuprate Bi_2Sr_2CuO_(6+δ)(Pb-Bi2201) and annealing them in vacuum or in high pressure oxygen atmosphere, a series of high quality Pb-Bi2201 single crystals are obtained with T_c covering from 17 K to non-superconducting in the overdoped region. High resolution angle resolved photoemission spectroscopy measurements are carried out on these samples to investigate the evolution of the Fermi surface topology with doping in the normal state. Clear and complete Fermi surfaces are observed and quantitatively analyzed in all of these overdoped Pb-Bi2201 samples. A Lifshitz transition from holelike Fermi surface to electron-like Fermi surface with increasing doping is observed at a doping level of ~0.35. This transition coincides with the change that the sample undergoes superconducting-to-non-superconducting states.Our results reveal the emergence of an electron-like Fermi surface and the existence of a Lifshitz transition in heavily overdoped Bi2201 samples. This provides important information in understanding the connection between the disappearance of superconductivity and the Lifshitz transition in the overdoped region.展开更多
In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of(Li1-xFex)OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from int...In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of(Li1-xFex)OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from intrinsic superconducting properties,such as Andreev reflection,electron-boson coupling,multigap superconductivity,d-wave and p-wave pairing symmetry,they cannot be accounted for by the modified Blonder–Tinkham–Klapwijk(BTK) model,but require to consider critical current effects arising from the junction geometry.Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage,in order to correctly deduce the properties of the superconducting state.展开更多
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFA0300300 and 2017YFA0302900the Strategic Priority Research Program(B)of Chinese Academy of Sciences under Grant Nos XDB07020300and XDB25000000+2 种基金the National Basic Research Program of China under Grant No 2015CB921300the National Natural Science Foundation of China under Grant Nos 11334010 and 11534007the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2017013
文摘By partially doping Pb to effectively suppress the superstructure in single-layered cuprate Bi_2Sr_2CuO_(6+δ)(Pb-Bi2201) and annealing them in vacuum or in high pressure oxygen atmosphere, a series of high quality Pb-Bi2201 single crystals are obtained with T_c covering from 17 K to non-superconducting in the overdoped region. High resolution angle resolved photoemission spectroscopy measurements are carried out on these samples to investigate the evolution of the Fermi surface topology with doping in the normal state. Clear and complete Fermi surfaces are observed and quantitatively analyzed in all of these overdoped Pb-Bi2201 samples. A Lifshitz transition from holelike Fermi surface to electron-like Fermi surface with increasing doping is observed at a doping level of ~0.35. This transition coincides with the change that the sample undergoes superconducting-to-non-superconducting states.Our results reveal the emergence of an electron-like Fermi surface and the existence of a Lifshitz transition in heavily overdoped Bi2201 samples. This provides important information in understanding the connection between the disappearance of superconductivity and the Lifshitz transition in the overdoped region.
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2015CB921000,2016YFA0300301,and 2017YFA0302902)the National Natural Science Foundation of China(Grant Nos.11674374 and 1474338)+5 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH008)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB07020100 and XDB07030200)the Beijing Municipal Science and Technology Project(Grant No.Z161100002116011)the Fonds de la Recherche Scientifique–FNRS and the ARC Grant 13/18-08 for Concerted Research Actions,financed by the French Community of Belgium(Wallonia-Brussels Federation)Jérémy Brisbois acknowledges the support from F.R.S.–FNRS(Research Fellowship)The work of Alejandro V Silhanek is partially supported by PDR T.0106.16 of the F.R.S.–FNRS
文摘In this work,we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of(Li1-xFex)OHFeSe,LiTi2O4,and La2-xCexCuO4.While these features are similar to those stemming from intrinsic superconducting properties,such as Andreev reflection,electron-boson coupling,multigap superconductivity,d-wave and p-wave pairing symmetry,they cannot be accounted for by the modified Blonder–Tinkham–Klapwijk(BTK) model,but require to consider critical current effects arising from the junction geometry.Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage,in order to correctly deduce the properties of the superconducting state.