New magnetic field dependence of Landau levels in a graphenelike structure
New magnetic field dependence of Landau levels in a graphenelike structure
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DOI：
10.1103/physrevlett.100.236405
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发表时间：
2008-06-13
影响因子：
8.6
通讯作者：
Montambaux, Gilles
中科院分区：
文献类型：
--
作者：
Dietl, Petra;Piechon, Frederic;Montambaux, Gilles
考虑磁场中蜂窝晶格上的紧束缚模型。对于特殊值的跳跃积分，色散关系是线性的一个方向和二次在其他。我们发现，在这种情况下，朗道能级的能量随场B的变化类似于[（n+ γ）B]（2/3）的γ（n）（B）。这一结果是从磁场中蜂窝晶格的紧束缚谱（Hofstadter谱）的低场研究以及在低场连续近似下的计算中得到的。后者将新的谱与修改后的四次振子的谱联系起来。发现所获得的值γ =1/2是由Berry相位的消除产生的。
We consider a tight-binding model on the honeycomb lattice in a magnetic field. For special values of the hopping integrals, the dispersion relation is linear in one direction and quadratic in the other. We find that, in this case, the energy of the Landau levels varies with the field B as epsilon(n)(B)similar to[(n+gamma)B](2/3). This result is obtained from the low-field study of the tight-binding spectrum on the honeycomb lattice in a magnetic field (Hofstadter spectrum) as well as from a calculation in the continuum approximation at low field. The latter links the new spectrum to the one of a modified quartic oscillator. The obtained value gamma=1/2 is found to result from the cancellation of a Berry phase.