In this article I give a pedagogical illustration of why the essential problem of high-Tc superconductivity in the cuprates is about how an antiferromagnetically ordered state can be turned into a short-range state by...In this article I give a pedagogical illustration of why the essential problem of high-Tc superconductivity in the cuprates is about how an antiferromagnetically ordered state can be turned into a short-range state by doping. I will start with half-filling where the antiferromagnetic ground state is accurately described by the Liang Doucot-Anderson （LDA） wavefunction. Here the effect of the Fermi statistics becomes completely irrelevant due to the no double occupancy constraint. Upon doping, the statistical signs reemerge, albeit much reduced as compared to the original Fermi sta- tistical signs. By precisely incorporating this altered statistical sign structure at finite doping, the LDA ground state can be recast into a short-range antiferromagnetic state. Superconducting phase coherence arises after the spin correlations become short-ranged, and the superconducting phase transition is controlled by spin excitations. I will stress that the pseudogap phenomenon naturally emerges as a crossover between the antiferromagnetic and superconducting phases. As a characteristic of non Fermi liquid, the mutual statistical interaction between the spin and charge degrees of freedom will reach a maximum in a high-temperature ＂strange metal phase＂ of the doped Mott insulator.展开更多
基金Acknowledgements I acknowledge useful discussions with P. W. Anderson, W.-Q. Chen, Z.-C. Gu, S.-P Kou, T. Li. J.-W. Mei, V. N. Muthukumar, H. T. Nieh, N. P. Ong, X.-L. Qi, Y. Qi, D.-N. Sheng, C.-S. Tian, Y.-Y. Wang, X.-G. Wen, K. Wu, P. Ye, J. Zaa- nen, F. Zhou, and Y. Zhou. I am grateful to Y.-Z. You＇s help with tile figures. This work was supported by tile National Natural Science Foundation of China （Grant No. 10834003） and the National Program for Basic Research of Ministry of Science and Technology （Grant Nos. 2009CB929402 and 2010CB923003）.
文摘In this article I give a pedagogical illustration of why the essential problem of high-Tc superconductivity in the cuprates is about how an antiferromagnetically ordered state can be turned into a short-range state by doping. I will start with half-filling where the antiferromagnetic ground state is accurately described by the Liang Doucot-Anderson （LDA） wavefunction. Here the effect of the Fermi statistics becomes completely irrelevant due to the no double occupancy constraint. Upon doping, the statistical signs reemerge, albeit much reduced as compared to the original Fermi sta- tistical signs. By precisely incorporating this altered statistical sign structure at finite doping, the LDA ground state can be recast into a short-range antiferromagnetic state. Superconducting phase coherence arises after the spin correlations become short-ranged, and the superconducting phase transition is controlled by spin excitations. I will stress that the pseudogap phenomenon naturally emerges as a crossover between the antiferromagnetic and superconducting phases. As a characteristic of non Fermi liquid, the mutual statistical interaction between the spin and charge degrees of freedom will reach a maximum in a high-temperature ＂strange metal phase＂ of the doped Mott insulator.
