Theoretical Study of Friction

摩擦力的理论研究

基本信息

批准号：
09640463
负责人：
MATSUKAWA Hiroshi
金额：
$ 2.05万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

We have studied the frictional phenomena of a 2-dimensional model in the presence of the periodic potential in addition to impurities. This model can be applied also to the magnetic flux lattice in film superconductors. It turned out that impurity can diminishes the static frictional force, there is a kind of quasi long range order in the moving lattice even in the presence of impurities and so on. This order exists in the transverse direction for any magnitude of the velocity and cause the transverse pinning, that is, the direction of motion does not change even though we apply external force in the transverse direction. Typical length scale of the order grows with increasing velocity and cause a peculiar behavior of the kinetic frictional force and the transverse pinning force. The velocity dependence of the latter becomes nonmonotonic, which is caused by the change of the discommensurate structure.CDW nonlinear electric conduction which is the manifestation of the macroscopic quantum tunneling is observed in experiments. Two-probe method was employed in the experiments. In order to observe the tunneling currents by this method both CDW's near the electrode and in the bulk must move by quantum tunneling. We have explained the experiments by considering both vortex ring formation as the tunneling process near the electrode and the kink-antikink pair formation as that in the bulk.We have calculated the flow and the work of two kinds of quantum ratchet model and shown that the flow of these systems is the manifestation of the new quantum mechanical phenomena resulting from the interaction with the heat bath.We have discussed the quantum tunneling of the commensurate CDW and shown that the impurity can assist the tunneling.

我们研究了二维模型在存在周期性势和杂质的情况下的摩擦现象。该模型也可以应用于薄膜超导体中的磁通晶格。事实证明，杂质可以减小静摩擦力，即使存在杂质等，移动晶格中也存在一种准长程有序性。对于任何大小的速度，该顺序都存在于横向上，并导致横向钉扎，即即使我们在横向上施加外力，运动方向也不会改变。订单的典型长度尺度随着速度的增加而增长，并导致动摩擦力和横向钉扎力的特殊行为。后者的速度依赖性变得非单调，这是由不通约结构的变化引起的。CDW非线性电导是宏观量子隧道效应的表现形式。实验采用双探针法。为了通过这种方法观察隧道电流，电极附近和本体中的 CDW 都必须通过量子隧道移动。我们通过将涡环的形成视为电极附近的隧道过程和将扭结-反扭结对的形成视为本体中的隧道过程来解释实验。我们计算了两种量子棘轮模型的流动和功，并表明这些系统的流动是由于与热浴相互作用而产生的新量子力学现象的表现。我们讨论了相称CDW的量子隧道效应，并表明杂质可以辅助隧道效应。