Low-frequency resistance noise spectroscopy is applied to investigate bulk single crystals of the intercalated ironselenide K_(x)Fe_(2-y)Se_(2) superconductors with different iron vacancy orders.Based on a generalized...Low-frequency resistance noise spectroscopy is applied to investigate bulk single crystals of the intercalated ironselenide K_(x)Fe_(2-y)Se_(2) superconductors with different iron vacancy orders.Based on a generalized fluctuation model,the well-observed resistance hump above 100 K is interpreted as an insulator-metal phase transition with a characteristic transition energy of 0.1-0.6 eV,indicating a highly inhomogeneous energy distribution configuration.In the superconducting transition regime,we find that the normalized resistance noise scales with resistance R excellently as S_(R)/R^(2)∝R^(l_(rs)) with the noise exponent lrs≈1.4.With reduced iron vacancy disordering in enhanced superconductivity K_(x)Fe_(2-y)Se_(2) crystals,the level of resistance fluctuations is greatly suppressed,suggesting a geometrical phase transition for conduction channel,which is directly related to the microstructure of the crystals.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774303 and 11574373)Joint Fund of Yunnan Provincial Science and Technology Department,China(Grant No.2019FY003008)。
文摘Low-frequency resistance noise spectroscopy is applied to investigate bulk single crystals of the intercalated ironselenide K_(x)Fe_(2-y)Se_(2) superconductors with different iron vacancy orders.Based on a generalized fluctuation model,the well-observed resistance hump above 100 K is interpreted as an insulator-metal phase transition with a characteristic transition energy of 0.1-0.6 eV,indicating a highly inhomogeneous energy distribution configuration.In the superconducting transition regime,we find that the normalized resistance noise scales with resistance R excellently as S_(R)/R^(2)∝R^(l_(rs)) with the noise exponent lrs≈1.4.With reduced iron vacancy disordering in enhanced superconductivity K_(x)Fe_(2-y)Se_(2) crystals,the level of resistance fluctuations is greatly suppressed,suggesting a geometrical phase transition for conduction channel,which is directly related to the microstructure of the crystals.
