In-plane magnetoelectric response in bilayer graphene
In-plane magnetoelectric response in bilayer graphene
复制标题
DOI：
10.1103/physrevb.100.075421
复制
发表时间：
2019-05
影响因子：
3.7
通讯作者：
M. Kammermeier;Paul Thomas Wenk;U. Zulicke
中科院分区：
文献类型：
--
作者：
M. Kammermeier;Paul Thomas Wenk;U. Zulicke
石墨烯双层显示出不同寻常的磁电响应，其大小由山谷同位旋密度控制，这使得将磁电行为与电子山谷联系起来成为可能。作为对以往研究的补充，我们考虑了平行于双层平面的静态均匀电场和磁场的影响。从紧束缚描述出发，利用拟简并微扰理论，导出了低能哈密顿量，包括所有相关的磁电项，其前因子用紧束缚参数表示。我们证实了预期的轴子型伪标量项的存在，它与先前得到的平面外对应项具有相同的符号和大约两倍的大小。此外，磁电张量的小的各向异性修正从根本上与偏层间跳跃参数${\ensureath{\Gamma}}_{4}$有关。我们讨论了通过光学导电性的不同特征来识别磁电效应的可能方法。
A graphene bilayer shows an unusual magnetoelectric response whose magnitude is controlled by the valley-isospin density, making it possible to link magnetoelectric behavior to valleytronics. Complementary to previous studies, we consider the effect of static homogeneous electric and magnetic fields that are oriented parallel to the bilayer's plane. Starting from a tight-binding description and using quasidegenerate perturbation theory, the low-energy Hamiltonian is derived, including all relevant magnetoelectric terms whose prefactors are expressed in terms of tight-binding parameters. We confirm the existence of an expected axion-type pseudoscalar term, which turns out to have the same sign and about twice the magnitude of the previously obtained out-of-plane counterpart. Additionally, small anisotropic corrections to the magnetoelectric tensor are found that are fundamentally related to the skew interlayer hopping parameter ${\ensuremath{\gamma}}_{4}$. We discuss possible ways to identify magnetoelectric effects by distinctive features in the optical conductivity.