Non-Fermi-liquid behavior and doping asymmetry in an organic Mott insulator interface

Abstract

High-TC superconductors show anomalous transport properties in their normal states, such as the bad-metal and pseudogap behaviors. To discuss their origins, it is important to speculate whether these behaviors are material-dependent or universal phenomena in the proximity of the Mott transition, by investigating similar but different material systems. An organic Mott transistor is suitable for this purpose owing to the adjacency between the two-dimensional Mott insulating and superconducting states, simple electronic properties, and high doping/bandwidth tunability in the same sample. Here we report the temperature dependence of the transport properties under electron and hole doping in an organic Mott electric-double-layer transistor. At high temperatures, the bad-metal behavior widely appears except at half filling regardless of the doping polarity. At lower temperatures, the pseudogap behavior is observed only under hole doping, while the Fermiliquid-like behavior is observed under electron doping. The bad-metal behavior seems a universal high-energy scale phenomenon, while the pseudogap behavior is based on lower energy scale physics that can be influenced by details of the band structure. arXiv:1909.03782v1 [cond-mat.str-el]

Simultaneous Control of Bandfilling and Bandwidth in Electric Double-Layer Transistor Based on Organic Mott Insulator κ-(BEDT-TTF)2Cu[N(CN)2]Cl

“…In this brief review, we introduce bandfilling-and bandwidth-control measurements in a transistor device based on an organic antiferromagnetic Mott insulator (Figure 1) [4][5][6]. We fabricated an electric double layer (EDL) transistor [7], which is a type of field-effect transistor, using an organic Mott insulator.…”

Electric Double Layer Doping of Charge-Ordered Insulators α-(BEDT-TTF)2I3 and α-(BETS)2I3

“…In α-(BETS) 2 I 3 , the gate-induced conductivity reaches~140 µS, which largely exceeds the Mott-Ioffe-Regel conductivity limit in two dimensions (e 2 /h,~38.7 µS), around which metallic conduction emerges in various field-effect devices [20][21][22]. However, we could not observe metallic conduction either.…”

“…µ FE under electron doping is 55 cm 2 /Vs at 40 K and shows a thermal activation behavior that is similar to the α-(BEDT-TTF) 2 I 3 device (Figure 5d). Under electron doping, the gate-induced conductivity ∆σ sufficiently exceeds the Mott-Ioffe-Regel conductivity limit in two dimensions (e 2 /h,~38.7 µS), around which the metallic conduction appears in Si-MOSFET [20] and devices based on κ-type BEDT-TTF salts [21,22]. However, ∆σ in α-(BETS) 2 I 3 EDLT does not show metallic conduction below the transition temperature of ∼ 50 K, as shown in Figure 6a.…”

“…under electron doping at 40 K and shows a thermal activation behavior that is similar to the αdevice (Figure 5d). Under electron doping, the gate-induced conductivity exceeds the Mott-Ioffe-Regel conductivity limit in two dimensions ( around which the metallic conduction appears in Si-MOSFET [20] and de κ-type BEDT-TTF salts [21,22]. However, in α-(BETS)2I3 EDLT does not conduction below the transition temperature of ~50 K, as shown in Figure nius plots of (Figure 6b) show that unlike in α-(BEDT-TTF)2I3, the act near the transition temperature significantly decreases with increasing po mechanism is unclear because the insulating state of α-(BETS)2I3 is not a s ordered state, and the insulating mechanism is under debate [14][15][16].…”

Petahertz non-linear current in a centrosymmetric organic superconductor

“…Resistivity anisotropy under hole doping is attributed to the van Hove singularity in the density of states 33 . Under photoirradiation, the situation is similar in the sense that the carriers in the HOMO band is largely transferred into an otherwise empty band through intramolecular charge motion by the strong light field.…”