Hitoshi Miyasaka tells Journal of Materials Chemistry about his hot paper.

1. Could you explain the significance of your article to the non-specialist?
Isolated magnetic chains cannot be a classical bulk magnet at finite temperatures: everybody knows this fact. Nevertheless, isolated Ising-type chains have the possibility to become a superparamagnet like a single-molecule magnet (SMM), which exhibits very slow relaxation of magnetization below so-called blocking temperatures: at significantly low temperatures, this material behaves as if it is a general "magnet" with field hysteresis. Such materials have been discovered in the beginning of this century and were named single-chain magnets (SCM). Their characteristic magnetization dynamics should be explained by a function of the intra-chain exchange coupling mediating Ising-type anisotropic spins (this is a characteristic point different from SMM). This article reveals the exchange dependence of the magnetization relaxation systematically investigating a family of ferromagnetic-type SCMs and SMMs.

2. What has motivated you to conduct this work?
With a background of SMM work started from the beginning of 1990s, I had a discussion with my friend Dr Rodolphe Clérac in 2000: Despite their discrete forms, metal clusters possessing uni-axial anisotropy can be SMMs. So, is the chain that SMMs are ferromagnetically connected a kind of SMM? This question was our start to conduct this work. Immediately, I had designed chain compounds using Mn(III) salen-type complexes based on an idea that the 1D assembly of the Mn(III) salen-type complexes makes it possible to easily align axes of Mn(III) ions. Our strategy has been rationally creating various SMMs and SCMs. Another motivation is that nobody knows the detail of SCM yet. The work on SCMs is a gold mine of new chemistry and physics and it is just getting started.

3. Where do you see this work developing in the future?
SMMs or SCMs as size-defined nano-sized magnets are potential candidates for information storage devices and quantum computing devices. Looking at their respective characters, SMM is better to control quantum tunneling of the magnetization for the design of the quantum computing devices, and SCM is better to get high blocking temperatures for the design of the information storage devices. I am more interested in a candidate for spintronics devices from their impressive anisotropic character. Anyway, work on SMM and SCM has a significant potential to create new research field in aspects not only of their fundamental science but also of their applications.

4. Are there any particular challenges facing future research in this area?
About physics on SCM, it is very important to reveal: (i) the correlation between the intra-chain correlation and the magnetization dynamics, (ii) the effect of inter-chain interaction to the intra-chain magnetization dynamics. In the point of creation of materials, to design a system conjugating SCM (or SMM) properties and electron transfers is my next target.

Hitoshi Miyasaka  is an associate professor at the Graduate School of Science, Tohoku University in Sendai. He obtained a Ph.D. from Kyushu University, and then joined the group of Prof. Susumu Kitagawa at Kyoto University and the group of Prof. Kim R. Dunbar at Texas A&M University in Texas USA as a postdoctoral researcher of JSPS (1998-2000). In October 2000-March 2006, he was an assistant professor at the Graduate School of Science, Tokyo Metropolitan University, and was also a research member of the PRESTO project of Japan Science and Technology Agency (JST) in 2002-2004. He received the Chemical Society of Japan Award for Young Chemists for 2003 and the Young Researcher Award of the Minister of Education, Culture, Sports, Science and Technology for 2006.