Metric anomalies arising from a distribution of point defects (intrinsic interstitials, vacancies, point stacking faults), thermal deformation, biological growth, etc. are well known sources of material inhomogeneity and internal stress. By emphasizing the geometric nature of such anomalies we seek their representations for materially uniform crystalline elastic solids. In particular, we introduce a quasi-plastic deformation framework where the multiplicative decomposition of the total deformation gradient into an elastic and a plastic deformation is established such that the plastic deformation is further decomposed multiplicatively in terms of a deformation due to dislocations and another due to metric anomalies. We discuss our work in the context of quasi-plastic strain formulation and Weyl geometry. We also derive a general form of metric anomalies which yield a zero stress field in the absence of other inhomogeneities and any external sources of stress.
Interplay of Spin and Lattice Degrees of Freedom in the Frustrated Antiferromagnet CdCr_2O_4: High-field and Temperature Induced Anomalies of the Elastic Constants
Observation of elastic anomalies driven by coexisting dynamical spin Jahn-Teller effect and dynamical molecular spin state in paramagnetic phase of the frustrated MgCr$_2$O$_4$$
超声波速度测量的镁铬尖晶石MgCr $_2$ O $_4$揭示弹性异常的顺磁相，其特征在于由于几何挫折。温度依赖性的四元剪切模量$(C_{11}-C_{12})/2$表现出巨大的居里型软化，这应该是在反铁磁相的自旋Jahn-Teller畸变的前兆。三角剪切模量$C_{44}$表现出非单调的温度依赖性，在$\sim$ 50 K处具有特征最小值，表明晶格与动态分子自旋态的耦合。这些结果强烈地表明顺磁相的动态自旋Jahn-Teller效应和动态分子自旋态共存，这与反铁磁相的磁结构有序和动态分子自旋态共存是一致的.
