一种测量热扩散率的空间分辨光学方法
A spatially resolved optical method to measure thermal diffusivity
AI总结：
本文提出一种重叠泵浦与探测光束的空间分辨光学热扩散率测量方法，实现微米级分辨率，并揭示多畴及掺杂非均匀钌酸盐中的局域热输运与转变温度差异。
摘要：
我们描述了一种光学方法，可在凝聚态物理研究所需的宽温度范围内，直接测量反射单晶样品随位置变化的热扩散率。该方法使用两束激光：一束作为源，对样品温度进行局部调制；另一束作为样品反射率的探针，而反射率是调制温度的函数。热扩散率由源信号与探针信号之间的相位延迟获得。我们将该技术与光学低温恒温器中的显微镜装置相结合，其中样品放置在三轴压电位移台上，从而能够进行空间分辨测量。此外，我们通过实验和数学证明，当两束激光重叠而非采用传统方式将其分离时，可以获得各向同性的面内扩散率，这进一步将空间分辨率提高到微米尺度，在研究非均匀或多畴样品时尤其有价值。我们详细讨论了该技术发挥作用的实验条件，并在两种化学计量比双层钌酸盐 Sr3Ru2O7 和 Ca3Ru2O7 上展示了其性能。空间分辨率使我们能够研究后者单个畴中的扩散率，并且我们发现了随温度变化的面内扩散率各向异性。最后，我们利用两束激光重叠所带来的增强空间分辨率，测量了 Ti 掺杂 Ca3Ru2O7 的随温度变化的扩散率，该材料表现出金属-绝缘体转变。我们观察到同一样品上的转变温度存在很大差异，这种差异源于掺杂非均匀性，并表明空间分辨技术在获取材料固有性质方面的强大能力。
英文摘要：
We describe an optical method to directly measure position-dependent thermal diffusivity of reflective single crystal samples across a broad range of temperatures for condensed matter physics research. Two laser beams are used, one as a source to locally modulate the sample temperature, and the other as a probe of sample reflectivity, which is a function of the modulated temperature. Thermal diffusivity is obtained from the phase delay between source and probe signals. We combine this technique with a microscope setup in an optical cryostat, in which the sample is placed on a 3-axis piezo-stage, allowing for spatially resolved measurements. Furthermore, we demonstrate experimentally and mathematically that isotropic in-plane diffusivity can be obtained when overlapping the two laser beams instead of separating them in the traditional way, which further enhances the spatial resolution to a micron scale, especially valuable when studying inhomogeneous or multidomain samples. We discuss in detail the experimental conditions under which this technique is valuable, and demonstrate its performance on two stoichiometric bilayer ruthenates: Sr3Ru2O7 and Ca3Ru2O7. The spatial resolution allowed us to study the diffusivity in single domains of the latter, and we uncovered a temperature-dependent in-plane diffusivity anisotropy. Finally, we used the enhanced spatial resolution enabled by overlapping the two beams to measure temperature-dependent diffusivity of Ti-doped Ca3Ru2O7, which exhibits a metal-insulator transition. We observed large variations of transition temperature over the same sample, originating from doping inhomogeneity, and pointing to the power of spatially resolved techniques in accessing inherent properties.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
