期刊
PHYSICAL REVIEW B
卷 79, 期 12, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.79.125403
关键词
Anderson model; Coulomb blockade; ferromagnetism; magnetoelectronics; renormalisation; spin Hamiltonians; spin polarised transport
资金
- HPC-EUROPA [RII3-CT-2003-506079]
- European Commission
- Ministry of Education of the Czech Republic [MSM 0021620834]
- Czech Science Foundation [202/08/0361]
- European Community's [FP7/2007-2013, 213609]
We study the competition between interference due to multiple single-particle paths and Coulomb interaction in a simple model of an Anderson-type impurity with local-magnetic-field-induced level splitting coupled to ferromagnetic leads. The model along with its potential experimental relevance in the field of spintronics serves as a nontrivial benchmark system where various quantum-transport approaches can be tested and compared. We present results for the linear conductance obtained by a spin-dependent implementation of the density-matrix renormalization-group scheme which are compared with a mean-field solution as well as a seemingly more advanced Hubbard-I approximation. We explain why mean field yields nearly perfect results while the more sophisticated Hubbard-I approach fails even at a purely conceptual level since it breaks hermiticity of the related density matrix. Furthermore, we study finite bias transport through the impurity by the mean-field approach and recently developed higher-order density-matrix equations. We found that the mean-field solution fails to describe the plausible results of the higher-order density-matrix approach both quantitatively and qualitatively, as it does not capture some essential features of the current-voltage characteristics such as negative differential conductance.
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