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Research Update: lattice dynamics of excitonic insulator Ta2Ni(Se1-xSx)5

What role does crystalline lattice play in the emergence of electronic order? Following our previous work on the excitonic soft mode and emergent coherence of Ta2NiSe5 (WebLink: npj Quantum Materials 6, 52 (2021) ArXiv Link: arXiv:2007.07344 PDF: File), we explore the lattice dynamics of the excitonic insulator candidate family Ta2Ni(Se1-xSx)5 by means of Raman scattering. Strong interactions between optical phonons …

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Research Update: electronic phase diagram of excitonic insulator Ta2Ni(Se1-xSx)5

Following our previous work on the excitonic soft mode and emergent coherence of Ta2NiSe5 (WebLink: npj Quantum Materials 6, 52 (2021) ArXiv Link: arXiv:2007.07344 PDF: File), we study the effect of sulfur doping on the excitonic ground state. The critical excitonic fluctuations diminish with the sulfur doping x, and eventually shift to high energies, which is characteristic of a quantum …

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Research Update: non-Kramers doublet ground state of the triangular-lattice spin-liquid candidate TbInO3

What is the relationship between the nature of a spin liquid (SL) and the crystal-field (CF) ground state? Layers of Tb ions in the ferroelectric insulator TbInO3 have been proposed to hold a two-dimensional SL ground state. By inelastic light-scattering experiments we demonstrate that the Tb ions have a non-Kramers doublet ground state, which supports …

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Critical charge fluctuations and quantum coherent state in excitonic insulator Ta2NiSe5

Pavel A. Volkov, Mai Ye, Himanshu Lohani, Irena Feldman, Amit Kanigel, Kristjan Haule, Girsh Blumberg (A) and (B): Raman response χ”aa and χ”ac in the aa and ac scattering geometries, respectively. (C) and (D): χ”aa and χ”ac in the range enclosed by the dashed white boxes in (A) and (B) on a linear frequency scale. Attraction between electrons in metals drives superconductivity – …

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New Paper Published: Random singlet state in Ba5CuIr3O12 single crystals

We study the thermodynamic and high-magnetic-field properties of the magnetic insulator Ba5CuIr3O12, which shows no magnetic order down to 2 K, consistent with a spin-liquid ground state. While the temperature dependence of the magnetic susceptibility and the specific heat shows only weak antiferromagnetic correlations, we find that the magnetization does not saturate up to a …

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New Paper Published: Superconductivity and phonon self-energy effects in Fe1+yTe0.6Se0.4

S.-F. Wu, A. Almoalem, I. Feldman, A. Lee, A. Kanigel, G. Blumberg We study Fe1+yTe0.6Se0.4 multi-band superconductor with Tc = 14K by polarization-resolved Raman spectroscopy. Deep in the superconducting state, we detect pair-breaking excitation at 45cm−1 (2∆ = 5.6 meV) in the XY (B2g) scattering geometry, consistent with twice of the super- conducting gap energy …

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Hsiang-Hsi Kung received APS 2020 Richard L. Green Dissertation Award

Richard L. Greene Dissertation Award recognizes doctoral thesis research of exceptional quality and importance in experimental condensed matter or experimental materials physics. Sean’s excellent dissertation, “Collective excitations in the antisymmetric channel of Raman spectroscopy”, is an outstanding contribution to the physics society.

New Paper Published: Lattice dynamics, crystal-field excitations and quadrupolar fluctuations of YbRu2Ge2

Multipolar interactions and related ordering phenomena have attracted great interest. Multipoles are related to exotic phases including possible multipole-fluctuation induced superconductivity and hidden-order phase. For a systematic investigation of the collective behaviors of multipole moments, f-electron systems are suitable choices since the interplay of spin and orbital degrees of freedom of f-electrons facilitates multipole formation. …

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