Anisotropic magnetoresistance and piezoelectric effect in GaAs Hall samples
Anisotropic magnetoresistance and piezoelectric effect in GaAs Hall samples
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DOI：
10.1103/physrevb.95.075410
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发表时间：
2017-02-08
影响因子：
3.7
通讯作者：
Ciftja, Orion
中科院分区：
文献类型：
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作者：
Ciftja, Orion
应用垂直于二维电子系统的强磁场会产生各种量子相，从不可压缩的量子霍尔液体到维格纳固体、电荷密度波和奇异的非阿贝尔态。在过去的 GaAs 霍尔电子样品实验中发现的一些量子相在某些弱磁场下表现出明显的各向异性磁阻值。我们认为这可能是由于砷化镓等半导体主体固有的压电效应所致。这种效应有可能产生足够的面内内部应变，电子可以感受到该内部应变，并决定高电阻和低电阻的方向。当维格纳固体、电荷密度波和各向同性液相的能量非常接近时，系统的整体稳定性对局域有序非常敏感，因此即使受到弱扰动（例如压电诱导的有效电子-电子相互作用）也会受到强烈影响，这种相互作用是各向异性的。在这项工作中，我们认为，即使在通常人们期望仅看到各向同性量子霍尔或各向同性费米液态的强磁场状态下，各向异性相互作用势也可以稳定电子的各向异性液相。我们使用这种方法来支持一个理论框架，该框架设想了最低朗道能级下电子各向异性液晶态的可能性。特别是，我们认为，对于给定的各向异性库仑相互作用势，电子的各向异性液态可以稳定在接近液-固转变区域的最低朗道能级，填充因子 v = 1/6。对旋转对称性破缺的液晶态的量子蒙特卡罗模拟表明，液晶秩序的稳定性与电子各向异性液体态的存在一致，该电子各向异性在填充因子 v = 1/6 的最低朗道能级下稳定。
Application of a strong magnetic field perpendicular to a two-dimensional electron system leads to a variety of quantum phases ranging from incompressible quantum Hall liquid to Wigner solid, charge density wave, and exotic non-Abelian states. A few quantum phases seen in past experiments on GaAs Hall samples of electrons show pronounced anisotropic magnetoresistance values at certain weak magnetic fields. We argue that this might be due to the piezoelectric effect that is inherent in a semiconductor host such as GaAs. Such an effect has the potential to create a sufficient in-plane internal strain that will be felt by electrons and will determine the direction of high and low resistance. When Wigner solid, charge density wave, and isotropic liquid phases are very close in energy, the overall stability of the system is very sensitive to local order and, thus, can be strongly influenced even by a weak perturbation such as the piezoelectric-induced effective electron-electron interaction, which is anisotropic. In this work, we argue that an anisotropic interaction potential may stabilize anisotropic liquid phases of electrons even in a strong magnetic field regime where normally one expects to see only isotropic quantum Hall or isotropic Fermi liquid states. We use this approach to support a theoretical framework that envisions the possibility of an anisotropic liquid crystalline state of electrons in the lowest Landau level. In particular, we argue that an anisotropic liquid state of electrons may stabilize in the lowest Landau level close to the liquid-solid transition region at filling factor v = 1/6 for a given anisotropic Coulomb interaction potential. Quantum Monte Carlo simulations for a liquid crystalline state with broken rotational symmetry indicate stability of liquid crystalline order consistent with the existence of an anisotropic liquid state of electrons stabilized by anisotropy at filling factor v = 1/6 of the lowest Landau level.