Xiao Qian, Janson Oleg, Francoual Sonia, Qiu Qingzheng, Li Qizhi, Zhang Shilong, Xie Wu, Bereciartua Pablo, van den Brink Jeroen, van Wezel Jasper, Peng Yingying
International Center for Quantum Materials, School of Physics, <a href="https://ror.org/02v51f717">Peking University</a>, Beijing 100871, China.
<a href="https://ror.org/04zb59n70">Institute for Theoretical Solid State Physics</a>, Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany.
Phys Rev Lett. 2024 Sep 20;133(12):126402. doi: 10.1103/PhysRevLett.133.126402.
Chiral phases of matter, characterized by a definite handedness, abound in nature, ranging from the crystal structure of quartz to spiraling spin states in helical magnets. In 1T-TiSe_{2} a source of chirality has been proposed that stands apart from these classical examples as it arises from combined electronic charge and quantum orbital fluctuations. This may allow its chirality to be accessed and manipulated without imposing either structural or magnetic handedness. However, direct bulk evidence that broken inversion symmetry and chirality are intrinsic to TiSe_{2} remains elusive. Here, employing resonant elastic x-ray scattering technique, we reveal the presence of circular dichroism, i.e., polarization dependence of the resonant diffraction intensity, up to ∼40% at forbidden Bragg peaks that emerge at the charge and orbital ordering transition. The dichroism varies dramatically with incident energy and azimuthal angle. Comparison to calculated scattering intensities traces its origin to bulk chiral electronic order in TiSe_{2} and establishes resonant elastic x-ray scattering as a sensitive probe to electronic chirality.
具有明确手性的手性物质相在自然界中广泛存在，从石英的晶体结构到螺旋磁体中的螺旋自旋态。在1T-TiSe₂中，人们提出了一种手性来源，它与这些经典例子不同，因为它源于电子电荷和量子轨道涨落的共同作用。这可能允许在不施加结构或磁手性的情况下访问和操纵其手性。然而，关于反演对称性破缺和手性是TiSe₂固有的直接体相证据仍然难以捉摸。在这里，我们采用共振弹性X射线散射技术，揭示了圆二色性的存在，即在电荷和轨道有序转变时出现的禁戒布拉格峰处，共振衍射强度的偏振依赖性，高达约40%。二色性随入射能量和方位角剧烈变化。与计算的散射强度比较表明，其起源于TiSe₂中的体相手性电子序，并将共振弹性X射线散射确立为电子手性的灵敏探针。
