Electronic states and molecular dynamics of single-component molecular conductors<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>[</mml:mo><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">tmdt</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mo>]</mml:mo></mml:mrow></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>M</mml:mi><mml:mo>=</mml:mo><mml:mtext>Ni</mml:mtext

Takagi, Ryuzo; Miyagawa, Kazuya; Yoshimura, Masahide; Gangi, Hiro; Kanoda, K.; Zhou, Biao; Idobata, Yuki; Kobayashi, Akiko

doi:10.1103/physrevb.93.024403

Cited by 13 publications

(22 citation statements)

References 28 publications

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“…In these systems, two pπ orbitals in M(tmdt) 2 accommodate two electrons, likely giving pπ-band semimetals; the ab-initio band structure calculation predicts small Fermi pockets 4,10,11 . As expected, Ni(tmdt) 2 and Pt(tmdt) 2 are metals 1, 10,12 and appreciable electron correlation was revealed by 13 C nuclear magnetic resonance (NMR) studies 13 .…”

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confidence: 69%

Spin-gapped Mott insulator with the dimeric arrangement of twisted molecules Zn(tmdt) 2

et al. 2017

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Abstract13 C nuclear magnetic resonance measurements were performed for a single-component molecular material Zn(tmdt) 2 , in which tmdt's form an arrangement similar to the so-called κ-type molecular packing in quasi-two-dimensional Mott insulators and superconductors. Detailed analysis of the powder spectra uncovered local spin susceptibility in the tmdt π orbitals. The obtained shift and relaxation rate revealed the singlet-triplet excitations of the π spins, indicating that Zn(tmdt) 2 is a spin-gapped Mott insulator with exceptionally large electron correlations compared to conventional molecular Mott systems. 1A new type of molecular conductors M(tmdt) 2 (M = Ni, Au, Pt, Cu, and Pd) are of current interest not only because it is the first molecular metal composed of a single molecular species 1 but also affords novel electronic states owing to the multi-orbital nature, which conventional charge-transfer salts do not possess. Furthermore, the systems of M(tmdt) 2 are expected to host highly correlated electrons compared with conventional molecular materials with dimeric molecular structures called 2 : 1 compounds, where a dimer playing as one lattice site accommodates one carrier and thus the on-site Coulomb repulsion U is reduced by the spatial extension of the dimer orbital. In case that one molecule accommodates one carrier as in some of the systems M(tmdt) 2 , the U is not reduced by the dimerization.The M(tmdt) 2 consists of a single molecular species in which a transition-metal ion, M, is coordinated by molecular ligands, tmdt, from both sides 2,3 . The pπ molecular orbitals extended over the tmdt ligand lie near the Fermi level, whereas the energy level of the dpσ molecular orbital located around M strongly depends on M. 4-7 For M = Cu, the dpσ orbital lies close to the pπ orbitals, leading to the formation of a dpσ-pπ multi-orbital system 5,7 ;indeed, NMR studies of Cu(tmdt) 2 found that the dpσ and pπ orbitals host antiferromagnetic and spin-gapped Mott subsystems, respectively 8,9 . For M = Ni, Pt and Zn, the dpσ orbitals lie away (upward in the former two and downward in the latter) from the two pπ orbitals located near the Fermi level 4,10 . In these systems, two pπ orbitals in M(tmdt) 2 accommodate two electrons, likely giving pπ-band semimetals; the ab-initio band structure calculation predicts small Fermi pockets 4,10,11 . As expected, Ni(tmdt) 2 and Pt(tmdt) 2 are metals 1,10,12 and appreciable electron correlation was revealed by 13 C nuclear magnetic resonance (NMR) studies 13 .It is to be noticed, however, that Zn(tmdt) 2 is an insulator 14 ; the typical resistivity data are shown in Fig. 1 Fig. 1(a). In the 2 solid, two tmdt ligands are arranged face-to-face and they form a checker-board pattern in two-dimensional layers (Figs. 1(b) and (c)). This type of molecular arrangement is similar to the "κ-type configuration", which is familiar in the 2 : 1 charge-transfer salts represented by κ-(ET) 2 X, including dimer-Mott insulators and over-10-K superconductors 15 . Most remarkably, Zn(tmdt)...

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confidence: 69%

Spin-gapped Mott insulator with the dimeric arrangement of twisted molecules Zn(tmdt) 2

et al. 2017

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“…In weakly correlated metals, the value of K (α) is around unity and is temperature independent, whereas it appreciably deviates from unity in strongly correlated metals [35,36]. For 200 to 300 K, K (α) takes ∼4, a value close to that of the pπ -band metal Ni(tmdt) 2 [20]…”

Section: B Relaxation Ratementioning

confidence: 93%

“…K iso potentially has an ambiguity in the chemical-shift determination, whereas K aniso is free from this problem; so, our analysis focuses on K aniso . Using the known spin susceptibility per tmdt, χ/2 [26], and the pπ anisotropic hyperfine coupling constant, B π = 3.6 kOe/(μ B tmdt) [20], we also calculated B π χ/2, which would give K aniso if the paramagnetic spins were solely on the pπ orbitals, and plotted them along with the K aniso values in Fig. 2(b).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…1(c), the pπ orbital can be viewed as a molecular orbital spatially localized on either of the tmdt ligands. Ni(tmdt) 2 , which accommodates two electrons in the two pπ orbitals, is a moderately correlated paramagnetic metal [9,20]. On the other hand, in Cu(tmdt) 2 , the dpσ orbital level comes down close to the two pπ orbitals and all three orbitals accommodate three electrons [19].…”

Section: Introductionmentioning

confidence: 99%

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Multiorbital antiferromagnetic metal induced by intramolecular self-doping

Takagi

Gangi

Miyagawa

et al. 2020

Phys. Rev. Research

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The orbital of electrons in a solid affects their mutual interaction, which is a key to emergent phenomena. Therefore, control of the interplay between distinct orbitals makes the behavior of solids fertile. Such a case is substantiated by the aggregation of the molecule, M(tmdt) 2 , which contains π orbitals extended over the organic ligand, tmdt, and a level-tunable d orbital centered at the metal ion M. Among them, Au(tmdt) 2 exemplifies the critical π-d mixing, which arguably causes an over-100 K antiferromagnetic metal whose nature remains elusive. Here, we track the π-d interplay in Au(tmdt) 2 with dual orbital-resolved probes, 13 C NMR and synchrotron x-ray diffraction. We find substantial intramolecular (interorbital) redistribution of electrons on cooling, triggering a commensurate π-d antiferromagnetic metal to emerge, which invokes an orbital-selective doped Mott insulator caused by intramolecular self-doping. This demonstrates that vital traffic of electrons between distinct orbitals brings about an unique correlated phase.

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“…give pπ band semimetals with appreciable electron correlation [12][13][14][15][16] . Contrastingly, the dpσ orbital lies close to the two pπ orbitals in the M = Cu 2+ system, which accommodates three electrons in the three orbitals 11 .…”

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confidence: 99%

Single-component molecular material hosting antiferromagnetic and spin-gapped Mott subsystems

Takagi¹,

Hamai²,

Gangi³

et al. 2017

Phys. Rev. B

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Electronic states and molecular dynamics of single-component molecular conductors[M(tmdt)2](M=Ni

Cited by 13 publications

References 28 publications

Spin-gapped Mott insulator with the dimeric arrangement of twisted molecules Zn(tmdt) 2

Spin-gapped Mott insulator with the dimeric arrangement of twisted molecules Zn(tmdt) 2

Multiorbital antiferromagnetic metal induced by intramolecular self-doping

Single-component molecular material hosting antiferromagnetic and spin-gapped Mott subsystems

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