A F Ioffe Institute, Russian Academy of Sciences, 194021 Saint Petersburg, Russia.
J Phys Condens Matter. 2010 Oct 13;22(40):405301. doi: 10.1088/0953-8984/22/40/405301. Epub 2010 Sep 20.
We observed a slow relaxation of the magnetoresistance in response to an applied magnetic field in selectively doped p-GaAs-AlGaAs structures with a partially filled upper Hubbard band. We have paid special attention to excluding the effects related to temperature fluctuations. Although these effects are important, we have found that the general features of slow relaxation persist. This behavior is interpreted as related to the properties of the Coulomb glass formed by charged centers with account taken of spin correlations, which are sensitive to an external magnetic field. Variation of the magnetic field changes the numbers of the impurity complexes of different types. As a result, it affects the shape and depth of the polaron gap formed at the states belonging to the percolation cluster responsible for the conductance. The suggested model explains both the qualitative behavior and the order of magnitude of the slowly relaxing magnetoresistance.
我们观察到，在部分填充上 Hubbard 带的选择性掺杂 p-GaAs-AlGaAs 结构中，磁阻对施加磁场的响应呈现缓慢弛豫。我们特别注意排除与温度波动相关的影响。尽管这些影响很重要，但我们发现，缓慢弛豫的一般特征仍然存在。这种行为被解释为与由带电中心形成的库仑玻璃的性质有关，考虑到自旋相关性，它对外磁场敏感。磁场的变化会改变不同类型的杂质复合物的数量。结果，它会影响形成于与负责电导的渗流团有关的状态的极化子能隙的形状和深度。所提出的模型解释了缓慢弛豫磁阻的定性行为和数量级。
