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Title: Novel Pd 2 Se 3 Two-Dimensional Phase Driven by Interlayer Fusion in Layered PdSe 2

Authors:
; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1368626
Grant/Contract Number:
FG02-09ER46554
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 119; Journal Issue: 1; Related Information: CHORUS Timestamp: 2017-07-06 22:09:53; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Lin, Junhao, Zuluaga, Sebastian, Yu, Peng, Liu, Zheng, Pantelides, Sokrates T., and Suenaga, Kazu. Novel Pd 2 Se 3 Two-Dimensional Phase Driven by Interlayer Fusion in Layered PdSe 2. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.119.016101.
Lin, Junhao, Zuluaga, Sebastian, Yu, Peng, Liu, Zheng, Pantelides, Sokrates T., & Suenaga, Kazu. Novel Pd 2 Se 3 Two-Dimensional Phase Driven by Interlayer Fusion in Layered PdSe 2. United States. doi:10.1103/PhysRevLett.119.016101.
Lin, Junhao, Zuluaga, Sebastian, Yu, Peng, Liu, Zheng, Pantelides, Sokrates T., and Suenaga, Kazu. Thu . "Novel Pd 2 Se 3 Two-Dimensional Phase Driven by Interlayer Fusion in Layered PdSe 2". United States. doi:10.1103/PhysRevLett.119.016101.
@article{osti_1368626,
title = {Novel Pd 2 Se 3 Two-Dimensional Phase Driven by Interlayer Fusion in Layered PdSe 2},
author = {Lin, Junhao and Zuluaga, Sebastian and Yu, Peng and Liu, Zheng and Pantelides, Sokrates T. and Suenaga, Kazu},
abstractNote = {},
doi = {10.1103/PhysRevLett.119.016101},
journal = {Physical Review Letters},
number = 1,
volume = 119,
place = {United States},
year = {Thu Jul 06 00:00:00 EDT 2017},
month = {Thu Jul 06 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on July 6, 2018
Publisher's Accepted Manuscript

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  • We used low-energy, momentum-resolved inelastic electron scattering to study surface collective modes of the three-dimensional topological insulators Bi 2Se 3 and Bi 0.5Sb 1.5Te 3-xSe x . Our goal was to identify the “spin plasmon” predicted by Raghu and co-workers [Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary collective mode is a surface plasmon arising from the bulk, free carriers in these materials. This excitation dominates the spectral weight in the bosonic function of the surface χ '' ( q , ω ) at THz energy scales, and is the most likely origin of a quasiparticlemore » dispersion kink observed in previous photoemission experiments. Our study suggests that the spin plasmon may mix with this other surface mode, calling for a more nuanced understanding of optical experiments in which the spin plasmon is reported to play a role.« less
  • We used low-energy, momentum-resolved inelastic electron scattering to study surface collective modes of the three-dimensional topological insulators Bi 2 Se 3 and Bi 0.5 Sb 1.5 Te 3 - x Se x . Our goal was to identify the “spin plasmon” predicted by Raghu and co-workers [Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary collective mode is a surface plasmon arising from the bulk, free carriers in these materials. This excitation dominates the spectral weight in the bosonic function of the surface χ '' ( q , ω ) at THz energy scales, and is themore » most likely origin of a quasiparticle dispersion kink observed in previous photoemission experiments. Our study suggests that the spin plasmon may mix with this other surface mode, calling for a more nuanced understanding of optical experiments in which the spin plasmon is reported to play a role« less
  • We report comprehensive 77 Se NMR measurements on a single crystalline sample of the recently discovered FeSe-based high-temperature superconductor K x Fe 2 - y Se 2 ( T c = 33 K) in a broad temperature range up to 290 K. Despite deviations from the stoichiometric KFe 2 Se 2 composition, we observed 77 Se NMR line shapes as narrow as 4.5 kHz under a magnetic field applied along the crystal c axis, and found no evidence for co-existence of magnetic order with superconductivity. On the other hand, the 77 Se NMR line shape splits into two peaks withmore » equal intensities at all temperatures when we apply the magnetic field along the ab plane. This suggests that K vacancies may have a superstructure and that the local symmetry of the Se sites is lower than the tetragonal fourfold symmetry of the average structure. This effect might be a prerequisite for stabilizing the s ± symmetry of superconductivity in the absence of the hole bands at the Brillouin zone center. From the increase of NMR linewidth below T c induced by the Abrikosov lattice of superconducting vortices, we estimate the in-plane penetration depth λ ab ~ 290 nm and the carrier concentration n e ~ 1 × 10 + 21 cm - 3 . Our Knight shift 77 K data indicate that the uniform spin susceptibility decreases progressively with temperature, in analogy with the case of FeSe ( T c ~ 9 K) as well as other FeAs high- T c systems. The strong suppression of 77 K observed immediately below T c for all crystal orientations is consistent with a singlet pairing of Cooper pairs. We do not however observe the Hebel-Slichter coherence peak of the nuclear spin-lattice relaxation rate 1 / T 1 immediately below T c , expected for conventional BCS s-wave superconductors. In contrast with the case of FeSe, we do not observe evidence for an enhancement of low-frequency antiferromagnetic spin fluctuations near T c in 1 / T 1 T . Instead, 1 / T 1 T exhibits qualitatively the same behavior as overdoped non-superconducting Ba(Fe 1 - x Co x ) 2 As 2 with x ~ 0 . 14 or greater, where hole bands are missing in the Brillouin zone center. We will discuss the implications of our results on the unknown mechanism of high-temperature superconductivity in FeSe and FeAs systems.« less