Development of New Method Enabling Writing/Overwriting/ Reading of Digital Information with Ultra-High Density More than 10 Times the Conventional Level on Carbon Molecule Thin Film

A group including Dr. Tomonobu Nakayama, a Group Leader in the International Research Center for Materials Nanoarchitectonics (MANA; Director-General: Masakazu Aono) at the National Institute for Materials Science (NIMS; President: Sukekatsu Ushioda), and Dr. Masato Nakaya, a NIMS Researcher, together with Prof. Yuji Kuwabara and members of the Division of Precision Science and Technology, Graduate School of Engineering, Osaka University, discovered a method which makes it possible to control the chemical reactions between functional molecules in molecular scale regions arbitrarily and with single molecule precision in chemical bonding between C₆₀ molecules, which are one of the molecules called “fullerenes” that have attracted attention in recent years. Based on this method, the group succeeded in the development of a new technology for storing non-volatile digital information in the recording medium with ultra-high density. This research achievement has the potential for development as a key technology for realizing high capacity, compact next-generation storage devices.

Focusing on the establishment of electronics driven by new principles, the research group developed a method enabling arbitrary control of the state in which the chemical bond between C₆₀ molecules undergo polymerization (bonded state) and depolymerization (unbonded state). In the present research, the group developed a method of storing digital information using an extremely thin film of fullerene C₆₀ molecules as the recording medium, and achieved ultra-high density approximately 1,000 times higher than of the high density information storage technology now in practical application, and more than 10 times higher than had been achieved with basic research-level technologies until now. Normally, C₆₀ molecules cohere by molecular force and form solid crystals. However, it was known that chemical bonds are formed between the molecules under high temperature, high pressure conditions or irradiation with an electron beam, etc. The development of the information storage method in the present research was carried out based on the discovery of a new method of room temperature control of the intended bonded/unbonded state of the C₆₀ molecules in the molecular thin film, and basic research which resulted in a detailed elucidation of the mechanism of this phenomena.

Systematic research in which a sharpened metal needle was placed in proximity to the recording medium and chemical reactions were induced in the C₆₀ molecules directly under the needle led to the discovery of a method that enables arbitrary selection of the bonded state and unbonded state of the C₆₀ molecules. When digital information was created using the bonded state (“1”) and unbonded state (“2”) and that information was stored, the group succeeded in recording, deleting, and rerecording the digital information with a surface density approximately 1,000 times higher than that of the existing storage devices. The stored information shows satisfactory non-volatility under room temperature conditions. In addition, the group devised a simple method of reading the “1” and “0” states and successfully demonstrated this method. The research group also succeeded in multi-value recording of “2”, “1”, and “0” by controlling the number of C₆₀ molecules.

  Details of this research are available online from the scientific journal Advanced Materials (publisher: Wiley-VCH; DOI: 10.1002/adma.200902960) and are now in the printing process. An international patent application (PCT/JP2008/054917) has been filed for recording medium and the method of information storage using the medium announced here.