Renormalization of single-ion magnetic anisotropy in the absence of the Kondo effect
Renormalization of single-ion magnetic anisotropy in the absence of the Kondo effect
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DOI：
10.1103/physrevb.97.075428
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发表时间：
2018-02-20
影响因子：
3.7
通讯作者：
Jacob, David
中科院分区：
文献类型：
--
作者：
Jacob, David
与量子自旋的单离子磁各向异性相关的非弹性自旋翻转激发可以通过近藤交换耦合到衬底中的传导电子来强烈重整化，如最近所示的情况下，在CuN 2岛上的Co吸附原子。在这种情况下，微分电导谱显示零偏压异常由于近藤效应的双简并基态，和有限偏置阶跃功能，由于自旋翻转激发。在这里，我考虑自旋-1量子磁体与正单轴各向异性，基态是非简并的，因此近藤效应不会发生。然而，非弹性自旋激发的重整化由于交换耦合的量子自旋与传导电子的杂交仍然发生，尽管在基态的近藤效应的完全缺乏。此外，我表明，远离粒子-空穴对称性，电荷波动有类似的效果近藤交换耦合，导致自旋翻转激发的重整化。然而，与近藤交换的重整化相反，电荷波动导致不对称光谱，对于强电荷波动，可以模仿Fano行为。
Inelastic spin-flip excitations associated with single-ion magnetic anisotropy of quantum spins can be strongly renormalized by Kondo exchange coupling to the conduction electrons in the substrate, as shown recently for the case of Co adatoms on CuN2 islands. In this case, differential conductance spectra show zero-bias anomalies due to a Kondo effect of the doubly degenerate ground state, and finite-bias step features due to spin-flip excitations. Here I consider spin-1 quantum magnets with positive uniaxial anisotropy, where the ground state is nondegenerate and hence the Kondo effect does not take place. Nevertheless, the renormalization of inelastic spin excitations due to exchange coupling by hybridization of the quantum spin with the conduction electrons still takes place despite the complete absence of the Kondo effect in the ground state. Additionally, I show that away from particle-hole symmetry, charge fluctuations have a similar effect to Kondo exchange coupling, leading to the renormalization of spin-flip excitations. However, in contrast to the renormalization by Kondo exchange, charge fluctuations lead to asymmetric spectra, which, for strong charge fluctuations, can mimic Fano behavior.