Anomalous scaling law for thermoelectric transport of 2D-confined electrons in an organic molecular system

Abstract

Confined electrons in low dimensions host desirable material functions for downscaled electronics as well as advanced energy technologies. Thermoelectricity is a most fascinating example, since the dimensionality modifies the electron density of states dramatically, leading to enhanced thermopower as experimentally examined in artificial two-dimensional (2D) structures. However, it is still an open question whether such an enhanced thermopower in low dimensions is realized in layered materials with strong 2D characters such as cuprates. Here, we report unusual enhancement of the thermopower in the layered organic compound $\alpha$-(BEDT-TTF)${}_2$I${}_3$, where BEDT-TTF stands for bis(ethylenedithio)-tetrathiafulvalene. We find that the slope in the Jonker plot (thermopower $S$ vs. logarithm of electrical conductivity $\log \sigma$) for $\alpha$-(BEDT-TTF)${}_2$I${}_3$ is significantly larger than that of conventional semiconductors. Moreover, the large slope is also seen in the related layered salt, demonstrating the impact of the 2D-confined carriers in the layered organics on thermoelectricity.

arXiv comment6 pages, 3 figures

References in corpus (14)

• Charge Ordering in alpha-(BEDT-TTF)2I3 by synchrotron x-ray diffraction
• Theoretical Aspects of Charge Ordering in Molecular Conductors
• Large Seebeck Effect by Charge-Mobility Engineering
• From Mott insulator to ferromagnetic metal: a pressure study of Ca${}_2$RuO${}_4$
• c-Axis Transport and Resistivity Anisotropy of Lightly- to Moderately-Doped La_{2-x}Sr_{x}CuO_{4} Single Crystals: Implications on the Charge Transport Mechanism
• Unusually large enhancement of thermopower in an electric field induced two-dimensional electron gas
• Ferroelectric properties of charge-ordered alpha-(BEDT-TTF)2I3
• Evidence for the coexistence of Dirac and massive carriers in a-(BEDT-TTF)2I3 under hydrostatic pressure
• Thermoelectric behavior of Ruddlesden-Popper series iridates
• Semimetallic and charge-ordered $\alpha$-(BEDT-TTF)${}_2$I${}_3$: on the role of disorder in dc transport and dielectric properties
• Colossal Seebeck coefficient of hopping electrons in (TMTSF)${}_2$PF${}_6$
• Anomalous Thermoelectric Response in an Orbital-Ordered Oxide Near and Far from Equilibrium
• Anomalous 2D-confined electronic transport in layered organic charge-glass systems
• Enhanced Seebeck coefficient through the magnetic fluctuations in Sr${}_2$Ru${}_{1-x}{M}_x$O${}_4$ ($M=$ Co, Mn)

Cited by in corpus (3)

• Negatively enhanced thermopower near a Van Hove singularity in electron-doped Sr${}_2$RuO${}_4$
• Carrier filtering effect for enhanced thermopower in a body-centered tetragonal ruthenate
• Thermoelectric transport properties of the quasi-one-dimensional dimer-Mott insulator ${\beta }^{\prime }$-(BEDT-TTF)${}_2$ICl${}_2$