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首页> 外文学位 >Magnetic field dependent properties of the Spin-Peierls chain in the organic conductor Per2Pt[mnt]2.
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Magnetic field dependent properties of the Spin-Peierls chain in the organic conductor Per2Pt[mnt]2.

机译：有机导体Per2Pt [mnt] 2中Spin-Peierls链的磁场依赖性。

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摘要

Nuclear magnetic resonance (NMR), susceptibility, and magnetic torque measurements were used to investigate the field-dependent properties of the localized magnetic moment in the two chain organic conductor Per 2Pt[mnt]2. At 8 K, the conducting (perylene) chain undergoes a lattice distortion resulting in a metal-insulator (M-I) transition and the formation of a charge density wave (CDW). Similarly, the magnetic (Pt[mnt] 2) chain undergoes a lattice distortion with the localized electrons ordering in an antiferromagnetic manner forming spin-singlet dimers in the spin-Peierls state at 6.5 K. The dimers and tetramers begin to break with increasing magnetic fields. At 20 T the system enters into a metallic state that persists up to 24 T. Dave Graf and his collaborators discovered a field induced charge density wave state (FICDW) from 24 T to 33 T using resisitivity measurements.;1H NMR is a localized probe sensitive to the spin dynamics of the Pt[mnt]2chain. Nuclear relaxation rates (T 1-1) and spectra reveal the SP-boundary occurs at a lower temperature than the CDW-boundary indicating the formation of the CDW precedes the dimerization on the Pt[mnt]2 chain. Furthermore, the boundaries at 20 T are concomitant and therefore the two chains are coupled up to high fields. The 45 T hybrid magnet was used to probe the physics of the magnetic chain in the FICDW state. Corresponding high field spectra, measured up to 32.5 T, reveal an increasing electronic spin polarization.;Activation energies and magnetic moments were extracted from fitting the temperature dependent T1 and susceptibility data revealing two competing spin systems in the low-temperature ground state; intrinisic behaviour of the dimerized system and a paramagnetic contribution possibly from dangling bonds or unpaired dimers accounting for less than 5 % of the Pt spins.;Additional measurements include 195Pt NMR and magnetic torque measurements using a piezoresistive cantilever (PRC). 195Pt NMR results show a strong orientational dependence while the PRC measurements confirm an increasing magnetization in the FICDW state. Finally future experiments will be discussed.
机译：核磁共振（NMR），磁化率和磁转矩测量用于研究两链有机导体Per 2Pt [mnt] 2中局部磁矩的场相关特性。在8 K时，导电（per）链经历晶格畸变，导致金属-绝缘体（M-I）跃迁并形成电荷密度波（CDW）。类似地，磁性（Pt [mnt] 2）链经历晶格畸变，局部电子以反铁磁方式有序排列，在6.5 K的自旋Peierls态下形成自旋单二聚体。随着磁场的增加，二聚体和四聚体开始断裂领域。在20 T时，系统进入金属状态，该状态持续到24T。DaveGraf和他的合作者通过电阻率测量发现了从24 T到33 T的场致电荷密度波态（FICDW）。;1H NMR是局部探针对Pt [mnt] 2链的自旋动力学敏感。核弛豫速率（T 1-1）和光谱表明，SP边界的发生温度低于CDW边界，这表明CDW的形成先于Pt [mnt] 2链上的二聚作用。此外，在20 T处的边界是伴随的，因此两条链耦合到高磁场。 45 T混合磁体用于探测FICDW状态下磁链的物理性质。高达32.5 T的相应高场谱显示出增加的电子自旋极化。通过拟合温度相关的T1提取了活化能和磁矩，磁化率数据揭示了两个竞争的自旋系统处于低温基态。二聚体系的内在行为以及悬挂键或未成对二聚体的顺磁贡献可能占不到Pt自旋的5％;其他测量包括195Pt NMR和使用压阻悬臂（PRC）的磁扭矩测量。 195Pt NMR结果显示出强烈的方向依赖性，而PRC测量证实FICDW状态下的磁化强度增加。最后，将讨论将来的实验。

著录项

  • 作者

    Green, Elizabeth L.;

  • 作者单位

    The Florida State University.;

  • 授予单位 The Florida State University.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 143 p.
  • 总页数 143
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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