We report a hydrothermal route to remove interstitial excess Fe in non-superconducting iron chalcogenide Fe_(1+δ)Se_(1-x)Te_(x) single crystals.The extra-Fe-free(δ~0)FeSe_(0.2)Te_(0.8) single crystal thus obtained s...We report a hydrothermal route to remove interstitial excess Fe in non-superconducting iron chalcogenide Fe_(1+δ)Se_(1-x)Te_(x) single crystals.The extra-Fe-free(δ~0)FeSe_(0.2)Te_(0.8) single crystal thus obtained shows bulk superconductivity at T_c~13.8 K,which is about 2 K higher than the FeSe_(0.2)Te_(0.8) sample obtained by usual postannealing process.The upper critical fieldμ_0H_(c2) is estimated to be~42.5 T,similar to the annealed FeSe_(0.2)Te_(0.8).It is surprising to find that the hydrothermal FeSe_(0.2)Te_(0.8)exhibits a remarkably small isothermal magnetization hysteresis loop at T=3 K.This yields an extremely low critical current density J_(c)~1.1×10^(2)A·cm^(-2)(over 100times smaller than the annealed FeSe_(0.2)Te_(0.8)) and indicates more free vortices in the hydrothermal FeSe_(0.2)Te_(0.8).展开更多
The intercalated iron selenide(Li,Fe)OHFeSe has a strongly layered structure analogous to the quasi-twodimensional(2D)bismuth cuprate superconductors,and exhibits both high-temperature(Tc)and topological superconducti...The intercalated iron selenide(Li,Fe)OHFeSe has a strongly layered structure analogous to the quasi-twodimensional(2D)bismuth cuprate superconductors,and exhibits both high-temperature(Tc)and topological superconductivity.However,the issue of its superconductivity dimensionality has not yet been fully investigated so far.Here we report that the quasi-2D superconductivity features,including the high anisotropyγ=151 and the associated quasi-2D vortices,are also revealed for(Li,Fe)OHFeSe,based on systematic experiments of the electrical transport and magnetization and model fittings.Thus,we establish a new vortex phase diagram for(Li,Fe)OHFeSe,which delineates an emergent quasi-2D vortex-liquid state,and a subsequent vortex-solid dimensional crossover from a pancake-like to a three-dimensional state with decreasing temperature and magnetic field.Furthermore,we find that all the quasi-2D characteristics revealed here for the high-Tciron selenide superconductor are very similar to those reported for high-Tcbismuth cuprate superconductors.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12061131005,11974019,11834016,and 11888101)the National Key Research and Development Program of China(Grant Nos.2022YFA1403900)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB33010200 and XDB25000000)the Chinese Academy of Sciences through the Youth Innovation Promotion Association(Grant No.2022YSBR-048)。
文摘We report a hydrothermal route to remove interstitial excess Fe in non-superconducting iron chalcogenide Fe_(1+δ)Se_(1-x)Te_(x) single crystals.The extra-Fe-free(δ~0)FeSe_(0.2)Te_(0.8) single crystal thus obtained shows bulk superconductivity at T_c~13.8 K,which is about 2 K higher than the FeSe_(0.2)Te_(0.8) sample obtained by usual postannealing process.The upper critical fieldμ_0H_(c2) is estimated to be~42.5 T,similar to the annealed FeSe_(0.2)Te_(0.8).It is surprising to find that the hydrothermal FeSe_(0.2)Te_(0.8)exhibits a remarkably small isothermal magnetization hysteresis loop at T=3 K.This yields an extremely low critical current density J_(c)~1.1×10^(2)A·cm^(-2)(over 100times smaller than the annealed FeSe_(0.2)Te_(0.8)) and indicates more free vortices in the hydrothermal FeSe_(0.2)Te_(0.8).
基金supported by the National Natural Science Foundation of China(Grant Nos.12061131005,11834016,and 11888101)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB33010200 and XDB25000000)。
文摘The intercalated iron selenide(Li,Fe)OHFeSe has a strongly layered structure analogous to the quasi-twodimensional(2D)bismuth cuprate superconductors,and exhibits both high-temperature(Tc)and topological superconductivity.However,the issue of its superconductivity dimensionality has not yet been fully investigated so far.Here we report that the quasi-2D superconductivity features,including the high anisotropyγ=151 and the associated quasi-2D vortices,are also revealed for(Li,Fe)OHFeSe,based on systematic experiments of the electrical transport and magnetization and model fittings.Thus,we establish a new vortex phase diagram for(Li,Fe)OHFeSe,which delineates an emergent quasi-2D vortex-liquid state,and a subsequent vortex-solid dimensional crossover from a pancake-like to a three-dimensional state with decreasing temperature and magnetic field.Furthermore,we find that all the quasi-2D characteristics revealed here for the high-Tciron selenide superconductor are very similar to those reported for high-Tcbismuth cuprate superconductors.
