First-principles study of spin-electric coupling in a {Cu3} single molecular magnet
First-principles study of spin-electric coupling in a {Cu3} single molecular magnet
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DOI：
10.1103/physrevb.82.155446
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发表时间：
2010-10-26
影响因子：
3.7
通讯作者：
Pederson, Mark
中科院分区：
文献类型：
--
作者：
Islam, M. Fhokrul;Nossa, Javier F.;Pederson, Mark
基于自旋密度泛函理论，研究了三角形反铁磁性{Cu3}单分子磁体的电磁性质。我们的计算表明，低能磁性可以用一个有效的三位自旋S=1/2海森伯模型来描述，反铁磁交换耦合J约为5 meV。该模型的基态流形由两个简并的自旋S=1/2手性相反的二重态组成。由于分子中缺乏反转对称性，即使在没有自旋-轨道相互作用的情况下，这两个态也会被外加电场耦合。自旋-电子耦合可以看作起源于电场引起的修正的交换常数J。我们发现，计算的手征态之间的跃迁速率得到了有效电偶极矩d=3.38×10(-33)Cm，近似于E10(-4)a，其中a是铜的分离度。对于约为10(8)V/m的外电场，该值对应于约为1 ns的Rabi时间tau和约为几微米eV的增量J。
We report on a study of the electronic and magnetic properties of the triangular antiferromagnetic {Cu3} single-molecule magnet, based on spin-density-functional theory. Our calculations show that the low-energy magnetic properties are correctly described by an effective three-site spin s = 1/2 Heisenberg model, with an antiferromagnetic exchange coupling J approximate to 5 meV. The ground-state manifold of the model is composed of two degenerate spin S = 1/2 doublets of opposite chirality. Due to lack of inversion symmetry in the molecule these two states are coupled by an external electric field, even when spin-orbit interaction is absent. The spin-electric coupling can be viewed as originating from a modified exchange constant delta J induced by the electric field. We find that the calculated transition rate between the chiral states yields an effective electric dipole moment d = 3.38 x 10(-33) C m approximate to e10(-4)a, where a is the Cu separation. For external electric fields epsilon approximate to 10(8) V/m this value corresponds to a Rabi time tau approximate to 1 ns and to a delta J on the order of a few mu eV.