自旋为1/2的XY模型亚铁磁棱型链的物性和有序-无序竞争  

Properties and order-disorder competition of spin-1/2 XY model in the ferrimagnetic diamond chain

作　　者：成泰民[1,2] 葛崇员[1] 孙树生[1] 贾维烨[1] 李林[3] 朱林[3] 马琰铭[2] 

机构地区：[1]沈阳化工大学数理系,沈阳110142 [2]吉林大学超硬材料国家重点实验室,长春130012 [3]东北大学物理系,沈阳110004

出　　处：《物理学报》2012年第18期484-495,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10647138);中国博士后科学基金(批准号:200904501018);国家重点基础研究发展计划(批准号:201 1CB606404)资助的课题~~

摘　　要：利用不变本征算符法,计算低温下自旋为1/2的XY模型—维亚铁磁棱型链系统的元激发谱,讨论在此系统中不同的特殊情形下的元激发能量,从而给出体系的三个临界磁场强度的解析解H_(C1),H_(C2),H_(peak).分析不同外磁场下体系的磁化强度随温度的变化规律,发现三个临界磁场强度的解析解H_(C1),H_(C2),H_(peak)是正确的,并从三个元激发对磁化强度的贡献进行了说明.低温下磁化强度随外磁场的变化呈现1/3磁化平台.体系的磁化率随温度或者外磁场的变化都出现了双峰现象.这说明双峰源于二聚体分子内电子自旋平行排列的铁磁交换作用能和二聚体与单基体分子间电子自旋反平行排列的反铁磁交换作用能,热无序能,外磁场强度相关的自旋磁矩势能之间的竞争.The elementary excitation spectra of the onedimensional spinl/2 XY model in the ferrimagnetic diamond cbain at low tem perature are calculated by using invariant eigenvector in this paper. And the elementary excitation energies in different cases are discussed. Therefore, analytic solutions of the three critical magnetic field intensities He1, He2 and//peak in the system are given. It is found that the analytic solutions of three critical magnetic field intensities are correct from the law of the magnetization changing with temperature under different external magnetic fields, and it is explained by the contributions of the three elementary excitations to the magnetization. The external magnetic field dependent magnetization presents a 1/3 magnetized plateau at low temperature. The variation of magnetic susceptibility either with temperature or with external magnetic field shows a double peak structure, this phe nomenon indicates that the double peak structure originates from the competition among the ferromagnetic exchange interaction energy of intramolecular electronic spin parallel arrangement in dimer, the antiferromagnetic exchange interaction energy of intermolecular electronic spin antiparallel arrangement in dimermonomer, the thermal disorder energy and the spin magnetic moment potential energy related to external magnetic field.

关 键 词：自旋为1/2的XY模型一维亚铁磁棱型链 磁化强度 磁化率 不变本征算符法 

分 类 号：O482.5[理学—固体物理]