scholarly journals Observation of perfect diamagnetism and interfacial effect on the electronic structures in infinite layer Nd0.8Sr0.2NiO2 superconductors

2021 ◽  
Author(s):  
Shengwei Zeng ◽  
Xinmao Yin ◽  
C. J. Li ◽  
Chi Sin Tang ◽  
K. Han ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Structure ◽  
Strain Effect ◽  
Material Synthesis ◽  
Infinite Layer ◽  
Sign Change ◽  
Key Points ◽  
X Ray Absorption ◽  
Structure Calculations

Abstract Nickel-based complex oxides have served as a playground for decades in the quest for a copper-oxide analog of the high-temperature (high-Tc) superconductivity. They may provide key points towards understanding the mechanism and an alternative route for high-Tc superconductors. The recent discovery of superconductivity in the infinite-layer nickelate thin films has fulfilled this pursuit. Thus far, however, material synthesis remains challenging. The demonstration of perfect diamagnetism is still missing, and understanding of the role of the interface and bulk to the superconducting properties is still lacking. Here, we synthesized high-quality Nd0.8Sr0.2NiO2 thin films with different thicknesses and investigated the interface and strain effects on the electrical, magnetic and optical properties. Perfect diamagnetism is demonstrated, confirming the occurrence of superconductivity in the thin films. Unlike the thick films in which the normal-state Hall coefficient (RH) changes signs as the temperature decreases, the RH of films thinner than 6.1 nm remains negative, suggesting a thickness-driven band structure modification. Moreover, X-ray absorption spectroscopy reveals the Ni-O hybridization nature in doped infinite-layer nickelates, and the hybridization is enhanced as the thickness decreases. Consistent with band structure calculations on the nickelate/SrTiO3 heterostructure, the interface and strain effect induce a dominating electron-like band in the ultrathin film, thus causing the sign change of the RH.

O 1s X-ray absorption spectra and band structure calculations of Ca1−xSrxRuO3

2004 ◽  
Vol 377 (1-2) ◽  
pp. 25-28 ◽  
Author(s):  
J. Manica ◽  
M. Abbate ◽  
J.E. Gayone ◽  
J.A. Guevara ◽  
S.L. Cuffini
Keyword(s):  
Band Structure ◽  
Absorption Spectra ◽  
X Ray ◽  
Band Structure Calculations ◽  
X Ray Absorption ◽  
Structure Calculations

Critical role of {002} preferred orientation on electronic band structure of electrodeposited monoclinic WO3 thin films

2018 ◽  
Vol 2 (10) ◽  
pp. 2224-2236 ◽  
Author(s):  
Wai Ling Kwong ◽  
Pramod Koshy ◽  
Judy N. Hart ◽  
Wanqiang Xu ◽  
Charles C. Sorrell
Keyword(s):  
Thin Films ◽  
Band Structure ◽  
Oxygen Vacancies ◽  
Electronic Band Structure ◽  
Critical Role ◽  
Preferred Orientation ◽  
Electronic Band ◽  
Wo3 Thin Films

Decoupled effects of crystallographic {002} orientation and oxygen vacancies on the electronic band structure of monoclinic WO3 films.

O 1s X-Ray Absorption Spectra and Band Structure Calculations of Ca1-xSrxRuO3.

ChemInform ◽  
2004 ◽  
Vol 35 (44) ◽  
Author(s):  
J. Manica ◽  
M. Abbate ◽  
J. E. Gayone ◽  
J. A. Guevara ◽  
S. L. Cuffini
Keyword(s):  
Band Structure ◽  
Absorption Spectra ◽  
X Ray ◽  
Band Structure Calculations ◽  
X Ray Absorption ◽  
Structure Calculations

scholarly journals Electronic structure of InN studied using soft x-ray emission, soft x-ray absorption, and quasiparticle band structure calculations

2007 ◽  
Vol 76 (24) ◽  
Author(s):  
L. F. J. Piper ◽  
Leyla Colakerol ◽  
Timothy Learmonth ◽  
Per-Anders Glans ◽  
Kevin E. Smith ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
X Ray ◽  
Band Structure Calculations ◽  
X Ray Absorption ◽  
Structure Calculations ◽  
Quasiparticle Band

Optical Properties of C60 and M6C60 (M=K, Rb, Cs) films

1992 ◽  
Vol 247 ◽  
Author(s):  
S. L. Ren ◽  
Ying Wang ◽  
M. Holden ◽  
A. M. Rao ◽  
F. Ni ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Structure ◽  
Photoelectron Spectroscopy ◽  
Normal Incidence ◽  
X Ray ◽  
Band Structure Calculations ◽  
Electron Energy Loss ◽  
Homo Lumo ◽  
Structure Calculations

ABSTRACTWe report the optical properties of C60 determined from the variable angle ellipsometry and near normal incidence reflection / transmission (R.T) experiments, and of M6C60 from the R, T experiments. The measurements were performed on thin films (d∼1000 Å) of C60 and M6C60 deposited on both Si(100) and suprasil substrates. The onset for strong absorption across the HOMO-LUMO gap in CgQ is measured to be -2.3 eV, slightly larger than the gap values obtained from the x-ray photoelectron spectroscopy (XPS) and electron-energy-loss spectroscopy (EELS) experiments. The observed peak positions in ε2(ω) for M6C60 and C60 compares well with the recent band structure calculations and suggests that the M6C60 compounds exhibit only a weak hybridization between the C60 and M states.

scholarly journals Detection of vancancies by using XAS, is it possible? The case of ZnO

2014 ◽  
Vol 70 (a1) ◽  
pp. C957-C957
Author(s):  
Clara Guglieri ◽  
Eva Céspedes ◽  
Carlos Prieto ◽  
Jesús Chaboy
Keyword(s):  
Thin Films ◽  
Magnetic Behaviour ◽  
Local Order ◽  
X Ray ◽  
Structural Distortions ◽  
Metal Doped ◽  
X Ray Absorption ◽  
Curie Temperatures ◽  
Shed Light

The occurrence of high temperature ferromagnetism (HTFM) in transition-metal-doped ZnO systems has attracted much attention in the last years. In particular, the Mn–Zn–O system has been widely studied and large efforts have been aimed at finding Curie temperatures above room temperature (RT). However the origin of that magnetic behaviour has not been explained yet. While doubts rise about the role of the 3d cations, several types of defects, such as oxygen and zinc vacancies, as well as hydrogen, oxygen and zinc interstitials, have been proposed by different authors to induce HTFM [1]. Aiming at determine the exact type of defect that causes the HTFM in these systems several experimental tools, such as x-ray absorption spectroscopy, have been applied. However, based on similar experimental spectra, different authors report opposing conclusions regarding the nature of defects involved in the observed HTFM [2,3]. These results pose serious doubts about the real capability of XAS to determine the presence of vacancies in these systems and, consequently, to shed light on the origin of the magnetism in these systems. Here we report a XANES study at both Mn and Zn K-edges in Zn(0.95)Mn(0.05)O thin films prepared with different sputtering gases (pure Ar, Ar/N2 and Ar/O2). We have studied the local order around Mn in the films, by means of ab initio XANES calculations. During this study, a special emphasis has been paid to determine the role played by both vacancies and structural distortions associated with the substitution of Zn by Mn in the ZnO host. Our results indicate that XANES is not sensitive to the presence of randomly distributed vacancies. On the contrary, the observed modifications of the XANES spectra are associated with the structural distortion around Mn sites, which rules the magnetic behaviour of these Mn:ZnO thin films in terms of the different sputtering gases involved in the preparation.

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