Phase evolution of the two-dimensional Kondo lattice model near half-filling
Phase evolution of the two-dimensional Kondo lattice model near half-filling
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二维近藤晶格模型接近半填充时的相演化
DOI：
10.1088/0953-8984/27/42/425601
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发表时间：
2015-06
期刊：
影响因子：
--
通讯作者：
于禄
中科院分区：
文献类型：
--
作者：
黎欢;刘瑜;张广铭;于禄
在平均场近似下，研究了二维Kondo晶格模型的基态相图和有限温度相图随Kondo耦合J和传导电子浓度nc>的变化.除了传统的局域矩和巡游电子之间的杂交，交错杂交提出了反铁磁性和近藤屏蔽效应之间的相互作用的特点。结果，获得了重费米子反铁磁相，并通过一级Lifshitz相变与纯反铁磁有序相分离，而重费米子反铁磁相和近藤顺磁相之间存在连续相变。我们已经开发了一个有效的理论来计算这些相界。作为NC？>从半填充开始减小，重费米子反铁磁相区域收缩，并在临界点nc*=0.8228？>处消失，对于nc，在纯反铁磁相和近藤顺磁相之间留下一阶临界线。在半填充极限下，在近藤耦合和温度（J-T）平面上确定了有限温度相图。值得注意的是，随着温度的升高，重费米子反铁磁相的区域不断减小，最后与纯反铁磁相和近藤顺磁相一起收敛到一个点。具有这种三相点的相图可以解释在相关重费米子材料中观察到的相变。
Within a mean-field approximation, the ground state and finite temperature phase diagrams of the two-dimensional Kondo lattice model have been carefully studied as functions of the Kondo coupling J and the conduction electron concentration nc ?>. In addition to the conventional hybridization between local moments and itinerant electrons, a staggered hybridization is proposed to characterize the interplay between the antiferromagnetism and the Kondo screening effect. As a result, a heavy fermion antiferromagnetic phase is obtained and separated from the pure antiferromagnetic ordered phase by a first-order Lifshitz phase transition, while a continuous phase transition exists between the heavy fermion antiferromagnetic phase and the Kondo paramagnetic phase. We have developed an efficient theory to calculate these phase boundaries. As nc ?> decreases from the half-filling, the region of the heavy fermion antiferromagnetic phase shrinks and finally disappears at a critical point nc*=0.8228 ?>, leaving a first-order critical line between the pure antiferromagnetic phase and the Kondo paramagnetic phase for nc. At half-filling limit, a finite temperature phase diagram is also determined on the Kondo coupling and temperature (J-T) plane. Notably, as the temperature is increased, the region of the heavy fermion antiferromagnetic phase is reduced continuously, and finally converges to a single point, together with the pure antiferromagnetic phase and the Kondo paramagnetic phase. The phase diagrams with such triple point may account for the observed phase transitions in related heavy fermion materials.
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DOI：
10.1007/978-94-011-5080-4_17
发表时间：
1979-09
期刊：
--
影响因子：
--
作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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