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Expanding Possibilities of π electrons in Molecular Conductors

Reizo Kato - RIKEN 2-1 Hirosawa, Wako-shi Saitama, 351-0198, Japan


Molecular conductors provide stages where π electrons play various roles. Our grand challenge is to expand possibilities of π electrons in molecular conductors and enhance their performance up to the limit. Our recent research topics are :

 

- π electrons in two-dimensional Mott system with a quasi-triangular lattice [1]

- Dual-faced π electron (itinerant electron and localized spin) [2]

- π electrons in Massless Dirac fermion state [3]

- Photo-induced transition in charge ordered π electron systems [4]

- Field effect transistor (FET) behavior of π electrons in organic Mott insulators [5].

 

The above phenomena are associated with various degrees of freedom, including charge, spin, lattice, and orbital.
Among them, I will focus on two strongly correlated electron systems :

 

1) Anion radical salts of M(dmit)2 (M=Ni, Pd) which show coexistence of itinerant electrons and localized spins (M=Ni) and the Mott insulating state with the spin frustration (M=Pd).

 

2) FET behavior of κ-(BEDT-TTF)2Cu[N(CN)2]Br thin crystal in the strain-induced Mott insulating state on the SiO2/Si substrate.

 

M(dmit)2 BEDT-TTF

References

[1] R. Kato, Chem. Rev., 104, 5319 (2004) ; M. Tamura et al., J. Phys. Soc. Jpn., 75, 093701 (2006) ; Y. Shimizu et al., Phys. Rev. Lett., 99, 256403 (2007) ; T. Itou et al., Phys. Rev. B, 77, 104413 (2008).

[2] Y. Kosaka et al., J. Am. Chem. Soc., 129, 3054 (2007).

[3] N. Tajima et al., Europhys. Lett. 80, 47002 (2007).

[4] N. Tajima et al., J. Phys. Soc. Jpn., 74, 511 (2005).

[5] Y. Kawasugi et al., Appl. Phys. Lett., 92, 243508 (2008).

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