This book reports the establishment of a single-atomic layer metal of In and a novel (In, Mg) ultrathin film on Si(111) surfaces. A double-layer phase of In called “rect” has been extensively investigated as a two-dimensional metal. Another crystalline phase called “hex” was also suggested, but it had not been established due to difficulty in preparing the sample. The author succeeded in growing the large and high-quality sample of the hex phase and revealed that it is a single-layer metal. The author also established a new triple-atomic layer (In, Mg) film with a nearly freestanding...