Abstract
A photoinduced phase transition was investigated in an organic charge-transfer (CT) complex M2P-TCNQF4, [M2P: 5,10-dihydro-5,10-dimethylphenazine, donor (D) molecule; TCNQF4: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, acceptor (A) molecule] by means of femtosecond pump-probe reflection spectroscopy. This is an ionic compound and has a peculiar two-dimensional (2D) molecular arrangement; the same A (or D) molecules arrange along the [100] direction, and A and D molecules alternately arrange along the [111] direction. It results in a strongly anisotropic two-dimensional electronic structure. This compound shows a structural and magnetic phase transition at 122 K below which the two neighboring molecules are dimerized along both the [100] and [111] directions. We demonstrate that two kinds of photoinduced phase transitions occur by irradiation of a femtosecond laser pulse; in the high-temperature lattice-uniform phase, a quasi-one-dimensional (1D) metallic state along the AA(DD) stack is generated, and in the low-temperature lattice-dimerized phase, a quasi-2D metallic state is initially produced and molecular dimerizations are subsequently released. Mixed-stack CT compounds consisting of DA stacks are generally insulators or semiconductors in the ground state. Here, such a dynamical metallization in the DA stack is demonstrated. The release of the dimerizations drives several kinds of coherent oscillations which play an important role in the stabilization of the lattice-dimerized phase. The mechanisms of those photoinduced phase transitions are discussed in terms of the magnitudes of the anisotropic bandwidths and molecular dimerizations along two different directions of the molecular stacks.
| Original language | English |
|---|---|
| Article number | 245140 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 91 |
| Issue number | 24 |
| DOIs | |
| Publication status | Published - Jun 18 2015 |
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ASJC Scopus subject areas
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials
Cite this
Photoinduced switching to metallic states in the two-dimensional organic Mott insulator dimethylphenazine-tetrafluorotetracyanoquinodimethane with anisotropic molecular stacks. / Matsuzaki, Hiroyuki; Ohkura, Masa Aki; Ishige, Yu; Nogami, Yoshio; Okamoto, Hiroshi.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 91, No. 24, 245140, 18.06.2015.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photoinduced switching to metallic states in the two-dimensional organic Mott insulator dimethylphenazine-tetrafluorotetracyanoquinodimethane with anisotropic molecular stacks
AU - Matsuzaki, Hiroyuki
AU - Ohkura, Masa Aki
AU - Ishige, Yu
AU - Nogami, Yoshio
AU - Okamoto, Hiroshi
PY - 2015/6/18
Y1 - 2015/6/18
N2 - A photoinduced phase transition was investigated in an organic charge-transfer (CT) complex M2P-TCNQF4, [M2P: 5,10-dihydro-5,10-dimethylphenazine, donor (D) molecule; TCNQF4: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, acceptor (A) molecule] by means of femtosecond pump-probe reflection spectroscopy. This is an ionic compound and has a peculiar two-dimensional (2D) molecular arrangement; the same A (or D) molecules arrange along the [100] direction, and A and D molecules alternately arrange along the [111] direction. It results in a strongly anisotropic two-dimensional electronic structure. This compound shows a structural and magnetic phase transition at 122 K below which the two neighboring molecules are dimerized along both the [100] and [111] directions. We demonstrate that two kinds of photoinduced phase transitions occur by irradiation of a femtosecond laser pulse; in the high-temperature lattice-uniform phase, a quasi-one-dimensional (1D) metallic state along the AA(DD) stack is generated, and in the low-temperature lattice-dimerized phase, a quasi-2D metallic state is initially produced and molecular dimerizations are subsequently released. Mixed-stack CT compounds consisting of DA stacks are generally insulators or semiconductors in the ground state. Here, such a dynamical metallization in the DA stack is demonstrated. The release of the dimerizations drives several kinds of coherent oscillations which play an important role in the stabilization of the lattice-dimerized phase. The mechanisms of those photoinduced phase transitions are discussed in terms of the magnitudes of the anisotropic bandwidths and molecular dimerizations along two different directions of the molecular stacks.
AB - A photoinduced phase transition was investigated in an organic charge-transfer (CT) complex M2P-TCNQF4, [M2P: 5,10-dihydro-5,10-dimethylphenazine, donor (D) molecule; TCNQF4: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, acceptor (A) molecule] by means of femtosecond pump-probe reflection spectroscopy. This is an ionic compound and has a peculiar two-dimensional (2D) molecular arrangement; the same A (or D) molecules arrange along the [100] direction, and A and D molecules alternately arrange along the [111] direction. It results in a strongly anisotropic two-dimensional electronic structure. This compound shows a structural and magnetic phase transition at 122 K below which the two neighboring molecules are dimerized along both the [100] and [111] directions. We demonstrate that two kinds of photoinduced phase transitions occur by irradiation of a femtosecond laser pulse; in the high-temperature lattice-uniform phase, a quasi-one-dimensional (1D) metallic state along the AA(DD) stack is generated, and in the low-temperature lattice-dimerized phase, a quasi-2D metallic state is initially produced and molecular dimerizations are subsequently released. Mixed-stack CT compounds consisting of DA stacks are generally insulators or semiconductors in the ground state. Here, such a dynamical metallization in the DA stack is demonstrated. The release of the dimerizations drives several kinds of coherent oscillations which play an important role in the stabilization of the lattice-dimerized phase. The mechanisms of those photoinduced phase transitions are discussed in terms of the magnitudes of the anisotropic bandwidths and molecular dimerizations along two different directions of the molecular stacks.
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U2 - 10.1103/PhysRevB.91.245140
DO - 10.1103/PhysRevB.91.245140
M3 - Article
AN - SCOPUS:84936806782
VL - 91
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 24
M1 - 245140
ER -