Using band structure parameters extracted from photoemission data by Yoshida et al., Phys. Rev. B., 2006, we have analyzed the temperature dependence of the superfluid density in overdoped La2-xSrxCuO4. We point out t...Using band structure parameters extracted from photoemission data by Yoshida et al., Phys. Rev. B., 2006, we have analyzed the temperature dependence of the superfluid density in overdoped La2-xSrxCuO4. We point out that the temperature behavior 1/λab2 is very sensitive to the ratio 2?0/kBTc and have estimated this quantity, using experimental data obtained previously by Panagopoulos et al., Phys. Rev. B., 1999. We compare the results with those obtained from NMR / NQR (Nuclear Magnetic Resonance / Nuclear Quadrupole Resonance) (Mayer et al., J. Phys, Cond. Mat., 2007) and scanning tunneling spectros-copy (Kato et al., Physica C, 2007) data.展开更多
Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. T...Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. The response of intrinsic electronic property of the crystals to the change of hole density in La2-xSrxCuO4 in the vicinity of the magic doping of x= 1/16 （= 0.0625） is studied in detail by magnetic measurements under various fields up to 1 T. It is found that when the superconducting critical temperature （Tc） increases with the oxygen content, there appears also a new subtle electronic state that can be detected from the differential curves of diamagnetic susceptibility dx/dT of the crystal sample. In contrast with the intrinsic state, the new subtle electronic state is very fragile under the magnetic fields. Our results indicate that a moderate change in oxygen doping does not significantly modify the intrinsic electronic state originally existing at the magic doping level.展开更多
Strontium and oxygen co-doped La1.937Sr0.063CuO4＋δ superconductor with Tc≈ 40K, which is obtained by oxidizing strontium-doped starting ceramic sample La1.937Sr0.063CuO4 in NaC10 solution, is annealed under differe...Strontium and oxygen co-doped La1.937Sr0.063CuO4＋δ superconductor with Tc≈ 40K, which is obtained by oxidizing strontium-doped starting ceramic sample La1.937Sr0.063CuO4 in NaC10 solution, is annealed under different conditions to allow interstitial oxygen to redistribute. The evolution of the intrinsic superconducting property with the oxygen redistribution is studied in detail by magnetic measurements in various fields. It is found that there occurs the electronic phase separation from the single superconducting phase with Tc ≈ 40 K into two coexisting superconducting states with values of Tc： 15 and 40K or of 15 and 35 K in this system, depending on annealing condition. Our results indicate that the 15, 35 and 40 K superconducting phases associated with the excess oxygen redistribution are all thermodynamically meta-stable intrinsic states in this Sr/O co-doped cuprate.展开更多
Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x= 0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studie...Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x= 0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studied, S remains positive, and with the increase of Sr concentration, room-temperature thermoelectric power S (290 K) decreases. An empirical formula which presents a relationship between hole concentration P and room-temperature thermoelectric power S (290 K) is reported in this note. Based on the theory of metallic diffusion model, the experimental results are discussed.展开更多
文摘Using band structure parameters extracted from photoemission data by Yoshida et al., Phys. Rev. B., 2006, we have analyzed the temperature dependence of the superfluid density in overdoped La2-xSrxCuO4. We point out that the temperature behavior 1/λab2 is very sensitive to the ratio 2?0/kBTc and have estimated this quantity, using experimental data obtained previously by Panagopoulos et al., Phys. Rev. B., 1999. We compare the results with those obtained from NMR / NQR (Nuclear Magnetic Resonance / Nuclear Quadrupole Resonance) (Mayer et al., J. Phys, Cond. Mat., 2007) and scanning tunneling spectros-copy (Kato et al., Physica C, 2007) data.
基金Project supported by the Ministry of Science and Technology of China (973 project Grant No 2006CB0L0302)the National Natural Science Foundation of China (Grant No 10574149)Chinese Academy of Sciences (Grant No KJCX2-SW-W18)
文摘Superconducting La1.937Sr0.063CuO4 crystals grown by the travelling-solvent floating-zone technique were thermally treated under various temperatures and oxygen pressures for moderately adjusting the oxygen content. The response of intrinsic electronic property of the crystals to the change of hole density in La2-xSrxCuO4 in the vicinity of the magic doping of x= 1/16 （= 0.0625） is studied in detail by magnetic measurements under various fields up to 1 T. It is found that when the superconducting critical temperature （Tc） increases with the oxygen content, there appears also a new subtle electronic state that can be detected from the differential curves of diamagnetic susceptibility dx/dT of the crystal sample. In contrast with the intrinsic state, the new subtle electronic state is very fragile under the magnetic fields. Our results indicate that a moderate change in oxygen doping does not significantly modify the intrinsic electronic state originally existing at the magic doping level.
基金supported by the State Key Development Program for Basic Research of China (Grant No 2006CB0L0302)the National Natural Science Foundation of China (Grant No 10574149)supported by European Union projectCoMePhS
文摘Strontium and oxygen co-doped La1.937Sr0.063CuO4＋δ superconductor with Tc≈ 40K, which is obtained by oxidizing strontium-doped starting ceramic sample La1.937Sr0.063CuO4 in NaC10 solution, is annealed under different conditions to allow interstitial oxygen to redistribute. The evolution of the intrinsic superconducting property with the oxygen redistribution is studied in detail by magnetic measurements in various fields. It is found that there occurs the electronic phase separation from the single superconducting phase with Tc ≈ 40 K into two coexisting superconducting states with values of Tc： 15 and 40K or of 15 and 35 K in this system, depending on annealing condition. Our results indicate that the 15, 35 and 40 K superconducting phases associated with the excess oxygen redistribution are all thermodynamically meta-stable intrinsic states in this Sr/O co-doped cuprate.
基金This work is partly supported by the National Natural Science Foundation of China (Grand No. 19904009)the Ministry of Science and Technology of China (NKBRSF-G1990646)the Natural Science Foundation of Zhejiang Province (Grand No. 199031).
文摘Thermoelectric power (S) measurements have been systematically investigated in high-quality La2-x-Srx-CuO4 single crystals with different Sr concentrations (x= 0.03, 0.05, 0.07, 0.1, 0.12). In this doping range studied, S remains positive, and with the increase of Sr concentration, room-temperature thermoelectric power S (290 K) decreases. An empirical formula which presents a relationship between hole concentration P and room-temperature thermoelectric power S (290 K) is reported in this note. Based on the theory of metallic diffusion model, the experimental results are discussed.
