Scanning tunneling microscopy studies on Zhang-Rice singlet state and high-TィイD2cィエD2 superconductivity

In the present study，we have been obtained the following results.1)In Bi2212and La214，the low temperature(T&lt；&lt；T I D2c文件D2)energy gap2ΔI D2o文件D2 increases with the lowering of the hole doping level p and scales with pseudogap temperature T文件D1*I D 1 over a wide p range；T I D 1*I D 1 is comparable to the mean-fieid T I D 2 c D 2(T I D 2 Co D 2)。This result provides a strong evidence for the pseudogap being related to the high-T I D2c锡D2 superconductivity.2)On the basis of the dependences of electronic specific heat and magnetic susceptibility，it was found that the superconducting critical fluctuation develops markedly below a certain temperature T I D2，~20%higher than T i D2 and much lower than T 1*D 2.This suggests that the motion of singlet pairs，whose formation will give rise to the pseudogap below~T i D1*I D 1，tends to become coherent below~T ii D 2 sf文件D2 to establish long-range phase coherence at T I D 2 c e D 2.3)In Bi2212 and La214，T I D 2 c D 2 nearly scales with pΔD 2 o I D 2.This indicates that the energy scale in determining T i D2c文件D2，is of the order of pΔI D2o文件D2，which is a striking feature of high-T文件D2c文件D2 cuprates，differing from that expected in conventional superconductors.In the present study，a scenario for the superconducting transition mechanism has also been proposed on the basis of the results mentioned above.

In the present study, we have been obtained the following results.1) In Bi2212 and La214, the low temperature (T<<TィイD2cィエD2) energy gap 2ΔィイD2oィエD2 increases with the lowering of the hole doping level p and scales with pseudogap temperature TィイD1*ィエD1 over a wide p range; TィイD1*ィエD1 is comparable to the mean-fieid TィイD2cィエD2(TィイD2coィエD2). This result provides a strong evidence for the pseudogap being related to the high-TィイD2cィエD2 superconductivity.2) On the basis of the dependences of electronic specific heat and magnetic susceptibility, it was found that the superconducting critical fluctuation develops markedly below a certain temperature TィイD2sf' ィエD2, 〜20% higher than TィイD2cィエD2 and much lower than TィイD1*ィエD1〜TィイD2coィエD2. This suggests that the motion of singlet pairs, whose formation will give rise to the pseudogap below 〜TィイD1*ィエD1, tends to become coherent below 〜TィイD2sfィエD2 to establish long-range phase coherence at TィイD2cィエD2.3) In Bi2212 and La214, TィイD2cィエD2 nearly scales with pΔィイD2oィエD2 ; kィイD2BィエD2TィイD2cィエD2〜pΔィイD2oィエD2. This indicates that the energy scale in determining TィイD2cィエD2, is of the order of pΔィイD2oィエD2, which is a striking feature of high-TィイD2cィエD2 cuprates, differing from that expected in conventional superconductors.In the present study, a scenario for the superconducting transition mechanism has also been proposed on the basis of the results mentioned above.