A simplification of the symmetric single‐impurity Kondo model is introduced and studied. In the Ising–Kondo model, host electrons scatter off a single magnetic impurity at the origin whose spin orientation is dynamically conserved. This reduces the problem to potential scattering of spinless fermions that can be solved exactly using the equation‐of‐motion technique. The Ising–Kondo model provides an example for static screening. At low temperatures, the thermodynamics at finite magnetic fields resembles that of a free spin‐1/2 in a reduced external field. Alternatively, the Curie law is interpreted in terms of an antiferromagnetically screened effective spin. The spin correlations decay algebraically to zero in the ground state and display commensurate Friedel oscillations. In contrast to the symmetric Kondo model, the impurity spin is not completely screened, i.e., the screening cloud contains less than a spin‐1/2 electron. At finite temperatures and weak interactions, the spin correlations decay to zero exponentially with correlation length ξ(T) = 1/(2πT).

中文翻译：

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Ising-Kondo模型中的热力学和筛选

引入并研究了对称单杂质近藤模型的简化。在Ising–Kondo模型中，主体电子在自旋取向动态保留的原点处散射出单个磁性杂质。这减少了无旋转费米子的潜在散射问题，可以使用运动方程技术精确解决该问题。Ising–Kondo模型提供了静态筛选的示例。在低温下，有限磁场下的热力学类似于外部磁场减小时自由自旋1/2的热力学。可替代地，居里定律根据反铁磁屏蔽的有效自旋来解释。自旋相关在基态中代数衰减为零，并显示出相应的Friedel振荡。与对称的近藤模型相比，杂质自旋未被完全屏蔽，即，屏蔽云中的电子少于自旋1/2。在有限的温度和弱相互作用下，自旋相关性随相关性长度呈指数衰减至零ξ（Ť）= 1 /（2π Ť）。