Fermi surface and anti-ferromagnetic order in 2D organic condutors

二维有机导体中的费米面和反铁磁序

• 批准号: 04640322
• 负责人: TOYOTA Naoki
• 金额: $ 1.54万
• 依托单位: Institute for Materials Research, Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640322/
• 关键词: Organic conductor; BEDFTTF Salt; (BEOT-TTF)_2KHg(SCN)_4; anti-ferromagnetic metal, quantum oscillation; 量子振動効果; スピン密度波

This research aims to study an organic conductor (BEDT-TTF) 2KHg-(SCN)4 which takes a phase transition from paramagnetic normal metal to antiferromagnetic metal at about 10K.This material, a typical quasi-two-dimensional conductor as well as other BEDT-TTF salts, shows quite unique properties such as, anomalous magnetoresistance below the transition point, splitting in the de-Haas quantum oscillations, and the reentrance to the normal metallic state above twenty several Tesla at low temperatures. We have studied these properties from the viewpoint of low-dimensional electronic states where closed 2D and open 1D Fermi surfaces coexist. We summarize the results as follows.1. We have found sharp increase in the Hall coefficient below the transition temperature. This suggests that the significant amount of carriers disappears, being not inconsistent with the appearance of spin- or charge-density-wave.2. We have systematically explained the origin of the splitting of de-Haas oscillations in terms of the positive (ferromagnetic) exchange interaction acting between the lower and upper Zeeman levels.3. Detailed studies for the in-plane current-direction dependence and the angular dependent oscillations of the magnetoresistance suggests that a new open orbit appears in the low temperature phase, pointing to the possible lattice displacement accompanied with the transition. We have pointed out the model on a basis of the coexistent SDW and CDW.

本研究旨在研究有机导体（BEDT-TTF） 2KHg-(SCN)4在10K左右发生顺磁性正常金属向反铁磁性金属相变的过程。该材料是一种典型的准二维导体，与其他BEDT-TTF盐一样，在过渡点以下表现出异常磁阻，在de-Haas量子振荡中分裂，以及在低温下在二十几个特斯拉以上重新进入正常金属态。我们从封闭二维和开放一维费米面共存的低维电子态的角度研究了这些性质。我们将结果总结如下。我们发现在转变温度以下霍尔系数急剧增加。这表明大量载流子消失了，这与自旋波或电荷密度波的出现并不矛盾。我们系统地解释了从上下塞曼能级之间的正（铁磁）交换相互作用的角度出发的去哈斯振荡分裂的起源。对磁阻的面内电流方向依赖和角依赖振荡的详细研究表明，在低温阶段出现了一个新的开放轨道，表明可能伴随着转变的晶格位移。我们在SDW和CDW共存的基础上提出了该模型。

项目成果

T.Sasaki: "Hall Effect in the Organic conductor α-(BEDT-TTF)_2KHg(SCN)_4 where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene" Phys.Rev.B. 48. 1928-1931 (1993)

T.Sasaki：“有机导体 α-(BEDT-TTF)_2KHg(SCN)_4 中的霍尔效应，其中 BEDT-TTF 是双(乙撑二硫)四硫富瓦烯”Phys.Rev.B. 48. 1928-1931 (1993)

T.Sasaki et al.: "Hall Effect in the Organic Conductor alpha-(BEDT-TTF)_2KHg(SCN)_4 where BEDT-TTF is bis(ethylene) dithiotetrathisfulvalene" Phys.Rev.B48. 1928-1931 (1993)

T.Sasaki 等人：“有机导体 α-(BEDT-TTF)_2KHg(SCN)_4 中的霍尔效应，其中 BEDT-TTF 是双（乙烯）二硫代四富瓦烯”Phys.Rev.B48。

M.Lang: "Magnetic Penetration Depth of k-(BEDT-TTF)_2 CuN(CN)_2Br determined by the Reuersible Magnetization" Phys.Rev.B. 46. 5822-5825 (1992)

M.Lang：“通过可重复磁化确定的 k-(BEDT-TTF)_2 CuN(CN)_2Br 的磁穿透深度”Phys.Rev.B。

T.Sasaki: "Magnetic Phase Diagram of the Organic Conductor α-(BEDT-TTF)_2KHg(SCN)_4" Solid State Commun.82. 447-451 (1992)

T.Sasaki：“有机导体 α-(BEDT-TTF)_2KHg(SCN)_4 的磁相图”Solid State Commun.82 (1992)。

M.Lang et al.: "Magnetic Penetration Depth of kappa-(BEDT-TTF)_2 CuN(CN)_2Br, determined by the reversible magnetization" Phys.rev.B46. 5822-5825 (1992)

M.Lang 等人：“kappa-(BEDT-TTF)_2 CuN(CN)_2Br 的磁穿透深度，由可逆磁化确定”Phys.rev.B46。