Mott insulator: K

The anion structure of the Mott insulator k-(ET)2Cu2(CN)3 34 in Fig. 21 revealed the disorder in the position of C and N atoms of the C=N groups (L2 part Table 6, Fig. 21a) [205-207, 370], due to the existence of an inversion center. However, NMR experiments observed very sharp resonance lines due to the homogeneous local field in the metallic state [371], which suggests that the C/N disorder, if any, does not work as the disorder potential in the conduction layer. 

Shimizu Y, Maesato M, Saito G, Drozdova O, Ouahab L (2003) Transport properties of a Mott insulator k-(ET)2Cu2(CN)3 under the uniaxial strain. Synth Met 133-134 225-226... 

Kezsmarki I, Shimizu Y, Mihaly G, Tokura Y, Kanoda K, Saito G (2006) Depressed charge gap in the triangular-lattice Mott insulator k-(ET)2Cu2(CN)3. Phys Rev B74 201101/1-4... 

Komatsu T, Saito G (1996) Carrier-doping in a Mott-insulator k-(BEDT-TTF)2Cu2(CN)3. Mol Cryst Liq Cryst 285 51-56... 

Terakura K, Williams A R, Qguchi T and Kubler J 1984 Transition-metal monoxides Band or Mott insulators Phys. Rev. Lett. 52 1830... 

O. K. (1991) Band theory and Mott insulators Hubbard Uinstead of Stoner I. Physical Review B - Condensed Matter, 44, 943-954. 

Table 6 Four typical K-type superconductors with Tc above 10 K (29 - 32) and a Mott insulator (34)...

Shimizu Y, Miyagawa K, Kanoda K, Maesato M, Saito G (2005) Spin liquid in a spin-frustrated organic Mott insulator. Prog Theor Phys Suppl 159 52-60... 

Komatsu T, Kojima N, Saito G (1997) Ambient-pressure superconductivity of k -(BEDT-TTF)2Cu2(CN)3 realized by a carrier-doping into a Mott-insulating state. Synth Met 85 1519-1520... 

Figure 27 Frequency-dependent conductivity of various TM2X compounds and 0(ET)2I3. DBTSF-TCNQ F4 is a Mott insulator at 300 K (after Ref. 96).

Terakura, K., A. R. Williams, T. Oguchi, and J. Kiibler (1984a). Transition-metal monoxides band or Mott insulators. Phys. Rev. Lett. 52, 1830-33. 

It should be added that the expansion of the tr-conjugating system and/or the introduction of Se atoms with greater polarizability (as shown in BETS or TTPs) reduce the effective on-site Coulomb energy U. For example, the V values for the TTP-type donors estimated from electrochemical and optical measurements are considerably small. (TTM-TTP)l3 is a 1 1 salt with a highly one-dimensional half-filled band. Although 1 1 salts were believed to be non-metal due to the Coulomb interaction (Mott-insulator), this salt shows metallic behavior down to about 160 K. This system is regarded as a small-f/ case of a one-dimensional conductor with an inherently half-filled band [27]. 

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