阻挫诱导的亚铁磁性Heisenberg系统中的量子相变  

Quantum phase transition as a result of magnetic frustrations in a ferrimagnetic Heisenberg system

作　　者：张松俊[1] 蒋建军[1] 刘拥军[1] 

机构地区：[1]扬州大学物理科学与技术学院,扬州225002

出　　处：《物理学报》2008年第1期531-534,共4页Acta Physica Sinica

基　　金：江苏省高校自然科学研究项目(批准号:05KJB14047)资助的课题~~

摘　　要：利用密度矩阵重整化群(DMRG)方法研究磁性阻挫对一种S=1/2准一维反铁磁自旋链但却具有亚铁磁性的Heisenberg系统基态的影响.计算了单个晶胞的基态能、自旋关联函数以及自旋能隙.研究表明这种Heisenberg自旋系统的基态随着阻挫α的增强将从磁有序相变化到自旋无序相,并且伴随着自旋能隙的出现,量子相变点为α≈0.412.同时线形链上格点间自旋长程关联值的计算结果表明在磁有序区间体系的磁有序性质随着α的增强而减弱,阻挫在0≤α<0.412的范围内还不足以破坏其亚铁磁性(非饱和铁磁行为).Using density-matrix renormalization group （DMRG） method, we studied the effect of magnetic frustrations due to next- nearest- neighbor bonds in a system of quasi-one-dimensional Heisenberg antiferromagnetic chain but with ferrimagnetic properties. In this paper, the ground state energy per unit cell, spin correlation function and spin gap are calculated. As a result of the frustrations, the quantum disordered phase with the spin gap appears at the spin order-disorder phase transition point αc≈0.412 to α= 1. And in the region of magnetic -order phase, the increasing magnetic frustrations reduce the magnetic order.

关 键 词：准一维反铁磁自旋链 亚铁磁性 密度矩阵重整化群 自旋能隙 

分 类 号：O481[理学—固体物理]