Indications for Lifshitz transitions in the nodal-line semimetal ZrSiTe induced by interlayer interaction

Signature of an Ultrafast Photo-Induced Lifshitz Transition in the Nodal-Line Semimetal ZrSiTe

Here we report an ultrafast optical spectroscopic study of the nodal-line semimetal ZrSiTe. Our measurements reveal that, converse to other compounds of the family, the sudden injection of electronic excitations results in a strongly coherent response of an $A_{1g}$ phonon mode which dynamically modifies the distance between Zr and Te atoms and Si layers. "Frozen phonon" DFT calculations, in which band structures are calculated as a function of nuclear position along the phonon mode coordinate, show that large displacements along this mode alter the material's electronic structure significantl…

Chemical pressure effect on the optical conductivity of the nodal-line semimetals ZrSi$Y$ ($Y$=S, Se, Te) and ZrGe$Y$ ($Y$=S, Te)

ZrSiS is a nodal-line semimetal, whose electronic band structure contains a diamond-shaped line of Dirac nodes. We carried out a comparative study on the optical conductivity of ZrSiS and related compounds ZrSiSe, ZrSiTe, ZrGeS, and ZrGeTe by reflectivity measurements over a broad frequency range combined with density functional theory calculations. The optical conductivity exhibits a distinct U shape, ending at a sharp peak at around 10000~cm$^{-1}$ for all studied compounds, except for ZrSiTe. The U shape of the optical conductivity is due to transitions between the linearly dispersing bands…

碱金属插层 1Tprime-MoTe2 中的 Lifshitz 转变与能带结构演化

Lifshitz Transition and Band Structure Evolution in Alkali Metal Intercalated 1Tprime-MoTe2

本研究结合 ARPES、STM、XPS 与 DFT，揭示室温钾处理通过碱金属插层使 1Tprime-MoTe2 在低浓度下发生 Lifshitz 转变、高浓度下产生显著能带重构。

层间关联淬灭配对破缺作为 La$_3$Ni$_2$O$_7$ 超导的关键

Quenched pair breaking by interlayer correlations as a key to superconductivity in La$_3$Ni$_2$O$_7$

研究通过团簇动力学平均场理论发现，La$_3$Ni$_2$O$_7$ 中的层间电子关联诱导 Lifshitz 相变并淬灭铁磁通道，从而增强 $s \pm$ 波配对不稳定性，解释了高压超导机制。

Ultrafast carrier-lattice interactions and interlayer modulations of Bi2Se3 by X-ray free electron laser diffraction

As a 3D topological insulator, bismuth selenide (Bi2Se3) has potential applications for electrically and optically controllable magnetic and optoelectronic devices. How the carriers interact with lattice is important to understand the coupling with its topological phase. It is essential to measure with a time scale smaller than picoseconds for initial interaction. Here we use an X-ray free-electron laser to perform time-resolved diffraction to study ultrafast carrier-induced lattice contractions and interlayer modulations in Bi2Se3 thin films. The lattice contraction depends on the carrier con…

Whirling interlayer fields as a source of stable topological order in moiré CrI3

The moiré engineering of two-dimensional magnets opens unprecedented opportunities to design novel magnetic states with promises for spintronic device applications. The possibility of stabilizing skyrmions in these materials without chiral spin-orbit couplings or dipolar interactions is yet to be explored. Here, we investigate the formation and control of ground state topological spin textures (TSTs) in moiré CrI3 using stochastic Landau-Lifshitz-Gilbert simulations. We unveil the emergence of interlayer vortex and antivortex Heisenberg exchange fields, stabilizing spontaneous and field-assist…