Direct measurement of temporal correlations above the spin-glass transition by coherent resonant magnetic x-ray spectroscopy
Jingjin Song, Sheena K. K. Patel, Rupak Bhattacharya, Yi Yang, Sudip Pandey, Xiao M. Chen, M. Brian Maple, Eric E. Fullerton, Sujoy Roy, Claudio Mazzoli, Chandr… 展开作者
Jingjin Song, Sheena K. K. Patel, Rupak Bhattacharya, Yi Yang, Sudip Pandey, Xiao M. Chen, M. Brian Maple, Eric E. Fullerton, Sujoy Roy, Claudio Mazzoli, Chandra M. Varma, Sunil K. Sinha
In the 1970s a new paradigm was introduced that interacting quenched systems, such as a spin-glass, have a phase transition in which long time memory of spatial patterns is realized without spatial correlations. The principal methods to study the spin-glass transition, besides some elaborate and elegant theoretical constructions, have been numerical computer simulations and neutron spin echo measurements . We show here that the dynamical correlations of the spin-glass transition are embedded in measurements of the four-spin correlations at very long times. This information is directly available in the temporal correlations of the intensity, which encode the spin-orientation memory, obtained by the technique of resonant magnetic x-ray photon correlation spectroscopy (RM- XPCS). We have implemented this method to observe and accurately characterize the critical slowing down of the spin orientation fluctuations in the classic metallic spin glass alloy Cu(Mn) over time scales of 1 to 1000 secs. Our method opens the way for studying phase transitions in systems such as spin ices, and quantum spin liquids, as well as the structural glass transition.
Origin of the glass-like dynamics in molecular metals $\pmbκ$-(BEDT-TTF)$_{\textbf{2}}$X: implications from fluctuation spectroscopy and $\pmb{\textit{ab initio}}$ calculations
Crossover from meta-magnetic state to spin-glass behaviour upon Ti-substitution for Mn in CuMn2O4
采用固相反应法制备了CuMn_（2-x）Ti_xO_4（x = 0，0.25和0.50）四元畸变尖晶石，并对其进行了中子衍射、红外光谱、介电谱和磁化强度测量。中子衍射和FTIR光谱提供了有关相形成的信息。磁化率表明，在低于76 K时，样品呈现亚铁磁有序结构，当Ti取代Mn时，样品的亚磁态转变为自旋玻璃行为。此外，所有尖晶石的室温M（H）都可用弱铁磁性的Arrott图描述。此外，室温介电测量提供了由晶界效应主导的CuMn 2 O 4的电子性质，该晶界效应在Ti取代CuMn 2 O 4中的Mn时显著增加。
Probing Anomalous Inelastic Scattering in Spin-ice Ho$_2$Ti$_2$O$_7$ through Resonant Raman Spectroscopy
研究了（001）和（111）Ho $_2$ Ti $_2$ O $_7$单晶的室温非弹性散射特性。结构和组成分析以及吸收测量证实了所有样品的单晶相。利用六条不同的激光激发线，在非共振和两种不同的共振条件下对晶体进行了室温偏振拉曼光谱测量。对所有测量的光谱进行洛伦兹模型拟合分析，以确定共振和非共振条件下拉曼散射截面的差异。由于不同的极化配置和晶体学取向的拟合参数的变化，有助于确定它们的对称性，如果存在的话。为了定性地解释Ho $_2$ Ti $_2$ O $_7$中的反常散射结果，讨论了几种可能的散射途径
Distinct amplitude mode dynamics upon resonant and off-resonant excitation across the charge density wave energy gap in LaTe3 investigated by time- and angle-resolved photoemission spectroscopy
Institute for Solid State Physics, The University of Tokyo（东京大学固体物理研究所）；Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University（斯坦福大学先进材料盖巴尔实验室与应用物理系）；Faculty of Physics, University of Duisburg-Essen（杜伊斯堡-埃森大学物理学院）
Manifestation of electron correlation effect in $\mathrm{U}~5f$ states of uranium compounds revealed by $\mathrm{U}~4d-5f$ resonant photoemission spectroscopy
