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Phenomenology of supersolids.

机译：超固体的现象学。

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摘要

We investigate the phenomenological properties of supersolids---materials that simultaneously display both crystalline order and superfluidity. To explain the recent observation in the torsional oscillator experiments on 4He solid by Kim and Chan we adopt a viscoelastic solid model which is characterized by a frequency-dependent complex shear modulus. In this model, we found that a characteristic time scale which accounts for dissipation in solids grows rapidly as the temperature is reduced, and results in a decrease in the resonant period and a peak in the inverse of Q-factor. We also briefly discuss the possible relation between the torsional oscillator results and the anomalous increase of shear modulus obtained by Day and Beamish.;In a related study, we employ a variational principle together with Galilean covariance and thermodynamic relations to obtain the non-dissipative hydrodynamics and an effective Lagrangian density for supersolids. We study the mode structure of supersolids by calculating the second and fourth sound speeds due to defect propagation. We also calculate the density-density correlation function of a model supersolid using the hydrodynamics of Andreev and Lifshitz, and propose a light scattering experiment to measure the density-density correlation function (which is related to the intensity of scattered light). We find that the central Rayleigh peak of the defect diffusion mode of a normal solid in the density-density correlation function splits into an additional Brillouin doublet due to the longitudinal second sound modes in supersolid phase.;Finally, we study the dynamics of vortices and dislocations in supersolids by using the derived Lagrangian for supersolids. We obtain the effective actions for vortices and dislocations in two-dimensional isotropic supersolids emphasizing the differences from the dynamics in superfluids and solids. As a result we obtain the frequency-dependent inertial masses for slowly moving vortices and dislocations.
机译：我们研究了超固体的现象学特性---同时显示结晶顺序和超流动性的材料。为了解释Kim和Chan对4He固体在扭转振荡器实验中的最新观察结果，我们采用了粘弹性固体模型，该模型的特征是频率相关的复数剪切模量。在该模型中，我们发现，随着温度降低，导致固体耗散的特征时间标度会迅速增长，并导致共振周期的减小和Q因子倒数的峰值。我们还简要讨论了扭振结果与Day和Beamish获得的剪切模量异常增加之间的可能关系。;在相关研究中，我们采用变分原理以及Galilean协方差和热力学关系来获得非耗散流体力学有效的拉格朗日密度。我们通过计算由于缺陷传播而产生的第二和第四声速来研究超固体的模态结构。我们还使用Andreev和Lifshitz的流体动力学来计算模型超固体的密度-密度相关函数，并提出了一个光散射实验来测量密度-密度相关函数（与散射光的强度有关）。我们发现，由于超固相中的纵向第二声模，普通固体在缺陷密度-密度相关函数中的缺陷扩散模式的中心瑞利峰分裂成一个额外的布里渊双峰。最后，我们研究了涡旋和通过使用派生的拉格朗日算子对超固体进行位错。我们获得了二维各向同性超固体中涡旋和位错的有效措施，强调了超流体和固体动力学的差异。结果，我们获得了慢速涡旋和位错的频率相关惯性质量。

著录项

  • 作者

    Yoo, Chi-Deuk.;

  • 作者单位

    University of Florida.;

  • 授予单位 University of Florida.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 128 p.
  • 总页数 128
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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