On the phase diagram of the attractive Hubbard model: Crossover and quantum critical phenomena
On the phase diagram of the attractive Hubbard model: Crossover and quantum critical phenomena
复制标题
关于有吸引力的哈伯德模型的相图：交叉和量子临界现象
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
M. H. Pedersen
中科院分区：
文献类型：
--
作者：
J. M. Singer;T. Schneider;M. H. Pedersen
翻译后摘要：我们探讨有吸引力的Hubbard模型的相变理论的观点的相图。利用量子蒙特-卡罗技术、量子临界现象的标度理论和XY模型的映射，我们研究了相图中沿着温度、能带填充和耦合强度轴的临界性质。特别强调的是致力于绝缘体到超导体和超导体到正常金属的转变驱动的耦合强度U的变化。我们还讨论了这种简单晶格模型和高Tc铜氧化物之间的特殊相似性：两个系统都表现出沿着某一临界线的相变，作为特定控制参数的函数，例如吸引耦合的强度|u|在Hubbard模型和铜氧化物平面中的电子掺杂的情况下，对于铜氧化物，两者都显示出沿着该相变线的显著交叉，具有类似的结果。在一个端点（过掺杂/小U制度），我们发现一个类似于传统的BCS型超导体的行为，该系统经历了正常的金属到超导体的转变（NS），而在另一端（欠掺杂/大U限制）的玻色-爱因斯坦凝聚（BEC）的预成型对的描述是更充分的，与超导体到绝缘体的临界端点（SI）。在那里，超导性发生在电子对的相位变得相干时，而不是在电子对最初形成时。除了固定的电子密度，相互作用驱动的交叉，Hubbard模型经历了进一步的T = 0量子跃迁，从（超）导体到绝缘体，
何 0 $$
.
Abstract:We explore the phase diagram of the attractive Hubbard model from the point of view of phase transition theory. Using the quantum Monte-Carlo technique, the scaling theory of quantum critical phenomena and the mapping to the XY model we investigate the critical properties along the temperature, band filling and coupling strength axes of the phase diagram. Particular emphasis is devoted to the insulator to superconductor and superconductor to normal metal transitions driven by the variation of the coupling strength U. We also discuss the particular similarities between this simple lattice model and the high-Tc cuprates: both systems exhibit a phase transition along a certain critical line as a function of a particular control parameter, which is e.g. the strength of the attractive coupling |U| in the case of the Hubbard model and the electron doping in the copper oxide planes for the cuprates; both show a remarkable crossover along this phase transition line with similar consequences. At one end point (overdoped/small-U regime) we find a behavior similar to a conventional BCS-type superconductor, the system undergoes a normal metal to superconductor transition (NS), whereas at the other end (underdoped/large-U limit) a description in terms of Bose-Einstein condensation (BEC) of preformed pairs is more adequate, with a superconductor to insulator critical endpoint (SI). There superconductivity occurs when the phases of the pairs become coherent, not when the pairs are initially formed. In addition to the fixed electron density, interaction driven crossover the Hubbard model undergoes a further T=0 quantum transition from a (super-) conductor to an insulator for $$
ho o 0$$
.