应用fermion－spin理论研究t－J模型的基态性质

FERMION-SPIN APPROACH TO STUDY THE t-J MODEL BASED ON THECHARGE-SPIN SEPARATION

应用ｆｅｒｍｉｏｎ－ｓｐｉｎ理论，研究了氧化物超导材料的基态性质。平均场结果说明在没有掺杂的半满情况下，系统处于磁性的π－ｆｌｕｘ状态。在掺杂情况下，讨论了系统的动能、相分离、与掺杂有关的反铁磁长程序等问题，结果与实验及数值模拟结果符合较好。

The ground-state properties of copper oxide materials are studied by using the fermion -spin transfornation. At half-filling,the mean field state with the lowest energy is the magnetized π-flus state. way from the half-filling. the mean-field ground-state kinetic energy is close to the numerical result at under dopings, and roughly consistent with the numerical result at optimal dopnigs. The antiferronmgnetic long-range order is destroyed for hole concentration less than 4.3%￣7% and the range of the phase separation is diminished to doping δ≤0.06 for the reasonable value of the parameters J'/J=0.05 and t/J=3￣5.