Reflectance of Dirac electrons in organic conductor

Yoshikazu Suzumura,Masao Ogata,Igor Proskurin

doi:10.1088/1742-6596/603/1/012011

Yoshikazu Suzumura, Masao Ogata + Show 1 more

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https://doi.org/10.1088/1742-6596/603/1/012011

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Abstract

We examine the reflectance R of Dirac electrons of organic conductor α-(BEDT- TTF)2I3 with a tilted cone which is characterized by a degree of the tilting η(= 0.8) and the angle a measured from the applied electric field. The reflectance is calculated using the complex dielectric constant, ε1 + iε2, which is evaluated from the in-plane dynamical conductivity with a constant damping Γ. The bulk reflectance on the two-dimensional plane is estimated by taking account of an interlayer distance of organic conductor α-(BEDT-TTF)2I3. We compare a difference of R between α = 0(i) and π/2 (ii), which correspond to the tilting being parallel and perpendicular to the electric field, respectively. The frequency ω dependence of R is examined for several magnitudes of the chemical potential μ to find a crossover from the zero doping to a finite doping. With increasing ω, R decreases from unity. For the small doping with μ < Γ, a difference of R between (i) and (ii) is small, while, for the large doping Γ < μ, a noticeable difference of R between (i) and (ii) exists in a certain region of ω around 2μ. The behavior that R of (ii) is larger than that of (i) is enhanced by the doping. We discuss the case of the clean limit and the role of both the intraband excitation and the interband excitation in the presence of Γ.

Highlights

The Dirac electrons in organic conductors have been studied extensively since the discovery in organic conductor α-(BEDT-TTF)2I3 [1] based on the X-ray Diffraction experiment [2]
Summary We examined the reflectance of Dirac electrons with a tilted cone using a parameter of organic conductor α-(BEDT-TTF)2I3, η = 0.8 and α = π/2 and 0
The reflectance on the plane is calculated from the dielectric constant which is estimated from the in-plane dynamical conductivity of the previous calculation

Summary

Introduction

The Dirac electrons in organic conductors have been studied extensively since the discovery in organic conductor α-(BEDT-TTF)2I3 [1] based on the X-ray Diffraction experiment [2]. The effect of tilting on the dynamical conductivity appears even for large frequency where the chemical potential is close to the onset of interband excitation [10]. By comparing with the isotropic case[11, 12], we show how the effect of tilting appears in the crossover from the intraband excitation to the interband excitation with increasing a frequency ω.

Results

Conclusion