High-pressure study of a Mott insulator (BEDT-TTF) (TCNQ)

Miyashita, M.; Uchiyama, Kenichi; Taniguchi, Hiromi; Satoh, Kazuhiko; Uwatoko, Yoshiya; Tajima, Naoya; Tamura, Masafumi; Kato, Reìzo

doi:10.1051/jp4:2004114075

Cited by 2 publications

(3 citation statements)

References 6 publications

(10 reference statements)

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“…6͑b͒, our results are plotted onto a P-T phase diagram of electrical conductivity measurements from two groups. 8,12 Although Iwasa et al 8 suggested that T N was thought to connect the metal-insulator transition line at high pressure, our results suggest that there is no connection between the metalinsulator transition line and T N above 1 GPa. On the other hand, Miyashita et al 12 claimed that metallic behavior has been observed at low temperatures and at 1.0 GPa.…”

Section: B Nmr Under Pressure and Phase Diagramcontrasting

confidence: 52%

“…8,12 Although Iwasa et al 8 suggested that T N was thought to connect the metal-insulator transition line at high pressure, our results suggest that there is no connection between the metalinsulator transition line and T N above 1 GPa. On the other hand, Miyashita et al 12 claimed that metallic behavior has been observed at low temperatures and at 1.0 GPa. Considering that the MI transition line from electrical conductivity is not connected with the line of the AF transition, MI transition at 50ϳ 100 K above 1.0 GPa is unlikely.…”

Section: B Nmr Under Pressure and Phase Diagramcontrasting

confidence: 52%

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Evidence for exchange interaction between donor and acceptor layers inβ′-(BEDT-TTF)(TCNQ)

et al. 2009

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We assessed the infrared-absorption spectra and 13 C-NMR measurements in a layered organic salt, ␤Ј-͑BEDT-TTF͒͑TCNQ͒, which exhibits antiferromagnetic transitions at 20 and 3 K. The former originates from the spin in the bis-͑ethylenedithio͒-tetrathiafulvalene ͑BEDT-TTF͒ layers, while the latter originates from the localized spin in the tetracyanoquinodimethane ͑TCNQ͒ layers. Using infrared-absorption spectroscopy, we estimated the degree of charge transfer, , between BEDT-TTF and TCNQ as 0.5. Using 13 C-NMR spectroscopy, we observed an exchange field at the BEDT-TTF site, which is produced by the localized spins of TCNQ dimers. Using the obtained value of and the molecular arrangement of ␤Ј-͑BEDT-TTF͒͑TCNQ͒, which is similar to that of the highest T c organic superconductor, ␤Ј-͑BEDT-TTF͒ 2 ICl 2 , we concluded that the absence of the pressure-induced superconductivity in ␤Ј-͑BEDT-TTF͒͑TCNQ͒ results from the presence of this exchange field. The exchange interaction, J, and the exchange field, H ex , were estimated as −12 K and −19 T / B on the TCNQ dimer unit, respectively. These findings suggest that superconductivity may arise in ␤Ј-͑BEDT-TTF͒͑TCNQ͒ by the application of an external field of 19 T under high pressure.

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Section: B Nmr Under Pressure and Phase Diagramcontrasting

confidence: 52%

Section: B Nmr Under Pressure and Phase Diagramcontrasting

confidence: 52%

Evidence for exchange interaction between donor and acceptor layers inβ′-(BEDT-TTF)(TCNQ)

et al. 2009

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“…This material consists of 2D donor ͑BEDT-TTF͒ sheets and one-dimensional ͑1D͒ acceptor ͑TCNQ͒ chains. In our previous report, 28 we almost metalized this organic material by applying pressure of 1.71 GPa by means of a piston-cylinder system including a MP35N cylinder and the ʈ -platform. 26 The electronic state of the material is semiconducting below room temperature.…”

Section: Application To Organic Conductorsmentioning

confidence: 99%

Short piston-cylinder pressure cells based on Ni–Cr–Al cylinders and their application to fragile materials

Taniguchi

Takeda

Satoh

et al. 2010

Review of Scientific Instruments

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In this decade, the performance of piston-cylinder pressure cells has been drastically improved by using robust materials such as nickel-chromium-aluminum and cobalt-nickel-chromium-molybdenum alloys to construct the inner cylinders. In this article, we present several experimental techniques for carrying out resistivity measurements under high pressure by applying the piston-cylinder devices based on the nickel-chromium-aluminum cylinders to fragile materials such as organics. These techniques are, in principle, applicable to measurements on any solid-state conductor. First, we introduce the construction of our piston-cylinder cells including two kinds of wired platforms for transport measurements. Second, we describe the construction of the platforms and the method of introducing the samples. After reporting test results for conventional materials such as ammonium fluoride, bismuth, and tellurium, lastly, we present examples of the successful application of our method to organic materials.

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High-pressure study of a Mott insulator (BEDT-TTF) (TCNQ)

Cited by 2 publications

References 6 publications

Evidence for exchange interaction between donor and acceptor layers inβ′-(BEDT-TTF)(TCNQ)

Evidence for exchange interaction between donor and acceptor layers inβ′-(BEDT-TTF)(TCNQ)

Short piston-cylinder pressure cells based on Ni–Cr–Al cylinders and their application to fragile materials

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