Lattice dynamics of KNi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>Se<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>

Lazarević, N.; Radonjić, Miloš M.; Šćepanović, M.; Lei, Hechang; Tanasković, D.; Petrović, C.; Popović, Zoran V.

doi:10.1103/physrevb.87.144305

Cited by 21 publications

(33 citation statements)

References 18 publications

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“…1(b) show one A 1g mode (177.9 cm −1 ) and one B 1g (132.8 cm −1 ) phonon, similar to the observation on the 122-ferropnictides [16], which share the same crystal structure. As illustrated in the inset, the intensity of these peaks are in perfect concordance with the four-fold symmetry of the crystal and the spectra are exempt of extra modes, which suggests that our TlNi 2 Se 2 samples are not phase-separated and do not show Ni vacancy ordering, in agreement with a previous study [17] on isostructural KNi 2 Se 2 . Fig.…”

supporting

confidence: 90%

Camelback-shaped band reconciles heavy-electron behavior with weak electronic Coulomb correlations in superconductingTlNi2Se2

Matt

Richard

et al. 2015

Phys. Rev. B

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Using high-resolution photoemission spectroscopy and first-principles calculations, we characterize superconducting TlNi2Se2 as a material with weak electronic Coulomb correlations leading to a bandwidth renormalization of 1.4. We identify a camelback-shaped band, whose energetic position strongly depends on the selenium height. While this feature is universal in transition metal pnictides, in TlNi2Se2 it lies in the immediate vicinity of the Fermi level, giving rise to a pronounced van Hove singularity. The resulting heavy band mass resolves the apparent puzzle of a large normal-state specific heat coefficient (Phys. Rev. Lett. 112, 207001) in this weakly correlated compound.

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supporting

confidence: 90%

Camelback-shaped band reconciles heavy-electron behavior with weak electronic Coulomb correlations in superconductingTlNi2Se2

Matt

Richard

et al. 2015

Phys. Rev. B

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“…43 According to previous Raman experiments and calculations on AT2X2 structures with I4/mmm symmetry (such as iron-chalcogenide compounds), defects such as vacancy ordering, consequently, symmetry lowering, may lead to the appearance of additional Raman peaks. 24,[44][45] As an evidence, in a previous high-quality Bi2O2Se sample, only one Raman peak located at about 160 cm −1 was also reported, 11 where the peak at 160 cm 1 can be assigned to the A1g mode…”

Section: Experimental Confirmationsmentioning

confidence: 83%

“…Ramon modes in similar systems AT2X2 (with I4/mmm group symmetry) have been successfully distinguished with such an approach. 24,48 Limited by the current sample condition, we did not pursue polarized Raman experiments here.…”

Section: Experimental Confirmationsmentioning

confidence: 99%

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Cheng¹,

Tan²,

Zhang

et al. 2018

J. Phys. Chem. C

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A new type of two-dimensional layered semiconductor with weak electrostatic but not van der Waals interlayer interactions, Bi2O2Se, has been recently synthesized, which shown excellent air stability and ultrahigh carrier mobility. Herein, we combined theoretical and experimental approaches to study the Raman spectra of Bi2O2Se and related bismuth oxychalcogenides (Bi2O2Te and Bi2O2S). The experimental peaks lie at 160 cm −1 in Bi2O2Se and at 147 cm −1 and 340 cm −1 in Bi2O2Te. They were fully consistent with the calculated results (159.89 cm −1 , 147.48cm −1 and 340.33 cm −1 ), and were assigned to the out-of-plane A1g, A1g and B1g modes, respectively. Bi2O2S was predicted to have more Raman-active modes due to its lower symmetry.The shift of the predicted frequencies of Raman active modes was also found to get softened as the interlayer interaction decreases from bulk to monolayer Bi2O2Se and Bi2O2Te. To reveal the strain effects on the Raman shifts, a universal theoretical equation was established based on the symmetry of Bi2O2Se and Bi2O2Te. It was predicted that the doubly degenerate modes split under in-plane uniaxial/shear strains. Under a rotated uniaxial strain, the changes of Raman shifts are anisotropic for degenerate modes although Bi2O2Se and Bi2O2Te were usually regarded as isotropic systems similar to graphene. This implies a novel method to identify the crystallographic orientation from Raman spectra under strain. These results have important consequences for the incorporation of 2D Bismuth oxychalcogenides into nanoelectronic devices.

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“…44 However, ordering of the vacancies, as reported for the K x Fe 2−δ Se 2 , 45 locally reduces the symmetry to I4/m. This leads to substantial increase in the number of Raman modes.…”

Section: 43mentioning

confidence: 99%

Insulating and metallic spin glass in Ni-dopedKxFe2−ySe2single crystals

et al. 2015

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We report electron doping effects by Ni in KxFe 2−δ−y NiySe2 (0.06 ≤ y ≤ 1.44) single crystal alloys. A rich ground state phase diagram is observed. Small amount of Ni (∼ 4%) suppressed superconductivity below 1.8 K, inducing insulating spin glass magnetic ground state for higher Ni content. With further Ni substitution, metallic resistivity is restored. For high Ni concentration in the lattice the unit cell symmetry is high symmetry I4/mmm with no phase separation whereas both I4/m + I4/mmm space groups were detected in the phase separated crystals when concentration of Ni < Fe. The absence of superconductivity coincides with the absence of crystalline Fe vacancy order.

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Lattice dynamics of KNi2Se2

Cited by 21 publications

References 18 publications

Camelback-shaped band reconciles heavy-electron behavior with weak electronic Coulomb correlations in superconductingTlNi2Se2

Camelback-shaped band reconciles heavy-electron behavior with weak electronic Coulomb correlations in superconductingTlNi2Se2

Raman Spectra and Strain Effects in Bismuth Oxychalcogenides

Insulating and metallic spin glass in Ni-dopedKxFe2−ySe2single crystals

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