ABSTRACT
Ballistic transport is a topic of increasing importance, owing to technical advances in top-down miniaturization capabilities. Another fundamental reason is the potential relevance for spintronic devices. že Datta and Das transistor device [1] relies on ballistic transport of the carrier, with a spin orientation modulated by external gating. In the ¢rst section, we will review the basic concepts related to ballistic transport properties, emphasizing the key characteristic lengths and dimensionalities. We will restrict our discussion to the simplest mathematical expressions and the most simplifying hypotheses. More comprehensive textbooks on mesoscopic electronics and ballistic transport in nanostructures can be found elsewhere [2,3]. We will emphasize the di¥erences between semiconductors and metallic nanostructures. Most experiments on ballistic transport were performed on semiconducting materials, taking advantage
of better control of their properties, and larger characteristic lengths. Experimental examples involving semiconductors are therefore more convincing and more detailed, and will be used as illustrations. We will then introduce spin-dependent ballistic transport, approaching its importance in the ¢eld of spin electronics. In the ¢nal section, experimental results on metallic structures will be presented.
