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arXiv 1806.06646cond-mat.mtrl-sci
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长程库仑相互作用对有机导体中无质量Dirac电子NMR位移的影响

Effect of Long-Range Coulomb Interaction on NMR Shift in Massless Dirac Electrons of Organic Conductor

Yoshikazu Suzumura

摘要:

本文研究了有机导体α-(BEDT-TTF)_2I_3中无质量Dirac电子的低温核磁共振(NMR)随位移的变化,其中四个分子在晶胞中的位址分别为A(= A '),B和C。狄拉克锥存在于导带和价带之间的0.01 eV的能量内。考虑到长程库仑相互作用和电子掺杂,计算了磁响应函数。在微扰中计算一级相互作用,自洽地确定化学势,并采用自能和顶点修正满足沃德恒等式。通过正确处理狄拉克锥的波函数,计算了0.0002 < T < 0.002(T是以eV为单位的温度)的低温下的位置相关位移。在较低(较高)的温度下,自能(顶点)校正的位移在所有网站,除了B是占主导地位的,符号是负(正),而在B网站的校正的符号总是负的。对于中等掺杂,作为T的函数的位移取最小值。的相关性的转变的实验进行了讨论。

英文摘要:

The nuclear magnetic resonance (NMR) with the site-dependent shift, at low temperatures is examined for a massless Dirac electrons in the organic conductor, alpha-(BEDT-TTF)_2I_3, where the sites of the four molecules in the unit cell are given by A (= A'), B, and C. The Dirac cone exists within an energy of 0.01 eV between the conduction and valence bands. The magnetic response function is calculated by taking account of the long-range Coulomb interaction and electron doping. Calculating the interaction within the first order in the perturbation, the chemical potential is determined self-consistently, and the self-energy and vertex corrections are taken to satisfy the Ward identity. The site-dependent shift is calculated at low temperatures of 0.0002 < T < 0.002 (T is temperature in the unit of eV) by correctly treating the wave function of the Dirac cone. At lower (higher) temperatures the self-energy (vertex) correction of the shift at all sites except for B is dominant and the sign is negative (positive), while the sign of the correction at the B site is always negative. For moderate doping, the shift as a function of T takes a minimum. The relevance of the shift to the experiment is discussed.

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