Field-induced antiferromagnetism in the Kondo insulator.
Field-induced antiferromagnetism in the Kondo insulator.
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DOI：
10.1103/physrevlett.92.026401
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发表时间：
2003-06
影响因子：
8.6
通讯作者：
Kevin Beach;P. Lee;P. Monthoux
中科院分区：
文献类型：
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作者：
Kevin Beach;P. Lee;P. Monthoux
近藤晶格模型，由塞曼项扩充，作为近藤绝缘体在外加磁场中的一个有用的模型。在量子蒙特卡罗计算的支持下，该系统在方形晶格上的变分平均场分析揭示了一个有趣的磁场尺度分离。对于与近藤能相当的塞曼能，自旋间隙闭合，系统形成横向交错磁序。然而，电荷间隙在更高的杂化能尺度上仍然保持稳定，此时倾斜的反铁磁性被指数抑制，系统跨越到接近金属的状态。量子蒙特卡罗模拟支持这种平均场场景。发现了谱权随磁场的有趣重排。
The Kondo lattice model, augmented by a Zeeman term, serves as a useful model of a Kondo insulator in an applied magnetic field. A variational mean field analysis of this system on a square lattice, backed up by quantum Monte Carlo calculations, reveals an interesting separation of magnetic field scales. For Zeeman energy comparable to the Kondo energy, the spin gap closes and the system develops transverse staggered magnetic order. The charge gap, however, remains robust up to a higher hybridization energy scale, at which point the canted antiferromagnetism is exponentially suppressed and the system crosses over to a nearly metallic regime. Quantum Monte Carlo simulations support this mean field scenario. An interesting rearrangement of spectral weight with magnetic field is found.