Surface vibrational modes of the topological insulator Bi2Se3 observed by Raman spectroscopy

Authors: H.-H. Kung, M. Salehi, I. Boulares, A.F. Kemper, N. Koirala, M. Brahlek, P. Lostak, C. Uher, R. Merlin, X. Wang, S.-W. Cheong, S. Oh, G. Blumberg Abstract: We present polarization resolved Raman scattering study of surface vibration modes in the topological insulator Bi2Se3 single crystal and thin films. Besides the 4 Raman active bulk …

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Superconductivity and electronic fluctuations in Ba_{1−x}K_{x}Fe_{2}As_{2} studied by Raman scattering

Authors: S.-F. Wu, P. Richard, H. Ding, H.-H. Wen, Guotai Tan, Meng Wang, Chenglin Zhang, Pengcheng Dai, G. Blumberg Abstract: Using polarization-resolved electronic Raman scattering we study underdoped, optimally doped, and overdoped Ba1−xKxFe2As2 samples in the normal and superconducting states. We show that low-energy nematic fluctuations are universal for all studied doping ranges. In the …

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Analogy between the `hidden order’ and the orbital antiferromagnetism in URu2Si2

Authors: H.-H. Kung, S. Ran, N. Kanchanavatee, V. Krapivin, A. Lee, J.A. Mydosh, K. Haule, M.B. Maple, and G. Blumberg Abstract: In URu2Si2 two types of staggered phases involving long range ordering of the uranium-5f electrons compete at low temperature when a critical parameter x is tuned, where x can be chemical substituent concentration, pressure …

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Collective excitations of dynamic Fermi surface deformations in BaFe2(As0.5P0.5)2

Authors: S.-F. Wu, W.-L. Zhang, D. Hu, H.-H. Kung, A. Lee, H.-C. Mao, P.-C. Dai, H. Ding, P. Richard and G. Blumberg Abstract: We use electronic Raman scattering to study the low-energy excitations in BaFe2(As0.5P0.5)2 (Tc≈16 K) samples. In addition to a superconducting pair breaking peak (2Δ=6.7 meV) in the A1g channel with a linear …

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Stress-induced nematicity in EuFe2As2 studied by Raman spectroscopy

Authors: W.-L. Zhang, Athena S. Sefat, H. Ding, P. Richard, and G. Blumberg Abstract: We use polarized Raman scattering to study the structural phase transition in EuFe2As2, the parent compound of the 122-ferropnictide superconductors. The in-plane lattice anisotropy is characterized by measurements of the side surface with different strains induced by different preparation methods. We …

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Raman scattering study of spin-density-wave-induced anisotropic electronic properties in AFe2As2 ( A = Ca, Eu)

Authors: W.-L. Zhang, Z. P. Yin, A. Ignatov, Z. Bukowski, Janusz Karpinski, Athena S. Sefat, H. Ding, P. Richard, and G. Blumberg Abstract: We present a polarization-resolved and temperature-dependent Raman scattering study of AFe2As2(A=Ca,Eu). In the spin-density-wave phase, spectral weight redistribution is observed in the fully symmetric and nonsymmetric scattering channels at different energies. An …

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