High-press. NMR　　　　　 Frustration　　　　 Mott-Insulator 　　　 Spin liquid　　　　 Orbital order

■ Mott transition and superconductivity from valence bond solid

In the strongly correlated electron system, the superconducting phase usually appears on the neighbor of long-range magnetic order phases. The superconductivity emerging from the disordered phase can be emergent. This is indeed realized in the organic Mott insulator EtMe3P[Pd(dmit)2]2 with triangular lattice [9]. The Pd(dmit)2 series organics provide Mott insulators with distorted triangular lattice. The magnetic phase diagram is summarized as a function of anisotropy of triangular lattice [10]. The EtMe3P salt exhibits the spin-dimerization at 25 K. The transition temperature decreases with increasing pressure and is terminated by the first-order Mott transition and the superconducting transition at 5 K. The reentrant transition and field-induced Mott transition evidences the VBS phase neighboring the superconducting phase.

References

  • [9] Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato
    "Mott Transition in a Valence-Bond Solid Insulator with a Triangular Lattice"
    Physical Review Letters 99, 256403 (2007).

  • [10] Y. Shimizu, H. Akimoto, H. Tsujii, A. Tajima, and R. Kato
    "Reentrant Mott transition from a Fermi liquid to a spin-gapped insulator in an organic spin-1/2 triangular-lattice antiferromagnet"
    J. Phys.: Condens. Matter 19(14), 145240/1-145240/5 (2007).


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