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Research Update:Anisotropy of Kondo-lattice coherence in momentum space for CeCoIn5
We study the electronic and phononic excitations of heavy-fermion metal CeCoIn5 by polarization- resolved Raman spectroscopy to explore the Kondo-lattice coherence. Below the coherence tempera- ture T* = 45 K, the continuum of electronic excitations in the XY scattering geometry is suppressed at frequencies below 50cm-1, whereas the low-frequency continuum in the X’Y’ geometry exhibits …
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Research Update: Chiral Electronic Excitations in a Quasi-2D Rashba System BiTeI
By comparing spectroscopic data to calculations within a three-band model, the CB1 band was confirmed to have a Rashba dispersion with parameters similar to those given by DFT: ∆1 = 1.48 eV, αR = 1.35 eV ̊A and m∗ = 0.15 me. The CB2 parabolic dispersion differs significantly from DFT calculations: (∆2 , m∗ ) …
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Research Update: Charge density wave order in the kagome metal AV3Sb5 (A = Cs,Rb,K)
Recently, a three-dimensional charge density wave order (a spatial modulation of electron charge density), which coexists with superconductivity at low temperatures, was discovered in AV3Sb5 (where A is Cesium, or Rubidium, or Potassium) kagome lattice (a geometrically-special atomic structure characterized by corner-sharing triangles). Researchers arise tremendous interest in this system as it is associated with …
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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 …
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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