Welcome to the Web page of the ESR Group.

In the ESR group, we utilize not only the conventional ESR equipments such as X-band, 9.5 GHz and Q-band, 34 GHz, but also ESR spectrometers with a very wide frequency range and under high pressures. This is a unique feature even worldwide. Of course, it is known that several groups have spectrometers with wide and higher frequency ranges (high magnetic fields), and are active in the studies of magnetic materials. The unique activity of the ESR group is in research with frequencies from several MHz to 24 GHz, and up to 94 GHz in collaboration with the Institute for Molecular Science (IMS).

The first example of the achievements with this technique is the neutral soliton dynamics in trans-polyacetylene (CH)_x. One of the main subjects in the ESR group is the organic one-dimensional (1D) electronic systems, with (CH)_x being an example. Another recent example with this technique is a highly 1D organic charge transfer salts, (DMe-DCNQI)₂Li that shows a spin-Peierls transition around 65 K, below which a non-magnetic ground state is formed. We have been successful in unveiling that the Curie-tail in the spin-Peierls state comes from the movable spin solitons as a domain wall. And more recently, the mechanism of the charge transport in the insulating 4k_F-CDW state above T_SP composed of DCNQI dimers was revealed; The hole solitons created through dissociation of dimers to pairs of fractionally charged solitons; a hole soliton with +e/2 and a spin soliton with -e/2 convey the charges not only along the chain, but also across the chains.

We have studied conducting polymers with ESR for many years. The wide band ESR study on the microscopic dynamics of the spins that convey charges has the unique advantage that the characteristic macromolecular structures of the polymers do not perturb this technique. A recent article summarizing this project is cited in the research subjects. A recent progress is on the alignment of the molecules/chains in the films of polypyrroles and polyalkylthiophenes, which not only affects the electronic states, but could also provide important information to unveil the origin of the properties of ESR in conducting polymers.

We also have found curious results on the magnetic fullerides, such as RbC₆₀ and TDAE-C₆₀, and organic crystals on the border of neutral-ionic character with ESR under high pressures. Recent analysis of the N-I transition in (BEDT-TTF)(ClMe TCNQ) demonstrated a comprehensive evolution of the ionic domain size through T_NI. Furthermore, with our unique technique, we plan to study the microscopic charge-carrier dynamics of DNA that has a nature of flexibly designable conducting polymers. DNA has been proposed to have electronic properties ranging from semiconducting to superconducting, which is promising for molecular electronics. In addition, it is also pointed out that DNA has a curious, interesting nature in basic physical aspects.