Composite Multiwalled Carbon Nanotubes as Memory Devices and Logic Gates

In this study, we propose a new nanocomputer component. We investigate the mechanics of a multiwalled carbon nanotube, comprising two symmetrically placed inner tubes and a moveable tube of radius intermediate to the larger and the two smaller tubes. The larger tube has the two fixed smaller tubes located at its ends, and the moveable tube is assumed to be controlled by an applied voltage difference. The tube radii are purposely chosen so that electrons can jump from one tube to another and a current can flow from the larger tube to the moveable one and finally to one of the smaller tubes. The interaction energy for the system is obtained assuming the Lennard-Jones potential together with the continuum approximation. As expected, the system has two symmetrically placed equal minimum energy locations (i.e., the total interaction energies take on minimum values) and by adopting different electrical circuits, the design gives rise to the possibility of using the device either as a memory device or as logic gates. By applying a voltage input to produce an external electrical field and another voltage input to provide a charge on the moving tube, the moving tube provides an output signal which we assume is registered on a meter that is capable of measuring either voltage or charge. We present the basic design rules for such devices and we establish their feasibility for practical realization.