scholarly journals Intertwined density waves in a metallic nickelate

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Junjie Zhang ◽  
D. Phelan ◽  
A. S. Botana ◽  
Yu-Sheng Chen ◽  
Hong Zheng ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Density Wave ◽  
Single Layer ◽  
Late Transition Metal ◽  
Density Waves ◽  
Paramagnetic Metal ◽  
Late Transition

AbstractNickelates are a rich class of materials, ranging from insulating magnets to superconductors. But for stoichiometric materials, insulating behavior is the norm, as for most late transition metal oxides. Notable exceptions are the 3D perovskite LaNiO3, an unconventional paramagnetic metal, and the layered Ruddlesden-Popper phases R4Ni3O10, (R = La, Pr, Nd). The latter are particularly intriguing because they exhibit an unusual metal-to-metal transition. Here, we demonstrate that this transition results from an incommensurate density wave with both charge and magnetic character that lies closer in its behavior to the metallic density wave seen in chromium metal than the insulating stripes typically found in single-layer nickelates like La2-xSrxNiO4. We identify these intertwined density waves as being Fermi surface-driven, revealing a novel ordering mechanism in this nickelate that reflects a coupling among charge, spin, and lattice degrees of freedom that differs not only from the single-layer materials, but from the 3D perovskites as well.

GW approximation study of late transition metal oxides: Spectral function clusters around Fermi energy as the mechanism behind smearing in momentum density

2016 ◽  
Vol 30 (14) ◽  
pp. 1650162
Author(s):  
S. M. Khidzir ◽  
K. N. Ibrahim ◽  
W. A. T. Wan Abdullah
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Fermi Energy ◽  
Momentum Density ◽  
The Self ◽  
Late Transition Metal ◽  
Gw Approximation ◽  
Self Energy ◽  
Late Transition

Momentum density studies are the key tool in Fermiology in which electronic structure calculations have proven to be the integral underlying methodology. Agreements between experimental techniques such as Compton scattering experiments and conventional density functional calculations for late transition metal oxides (TMOs) prove elusive. In this work, we report improved momentum densities of late TMOs using the GW approximation (GWA) which appears to smear the momentum density creating occupancy above the Fermi break. The smearing is found to be largest for NiO and we will show that it is due to more spectra surrounding the NiO Fermi energy compared to the spectra around the Fermi energies of FeO and CoO. This highlights the importance of the positioning of the Fermi energy and the role played by the self-energy term to broaden the spectra and we elaborate on this point by comparing the GWA momentum densities to their LDA counterparts and conclude that the larger difference at the intermediate level shows that the self-energy has its largest effect in this region. We finally analyzed the quasiparticle renormalization factor and conclude that an increase of electrons in the [Formula: see text]-orbital from FeO to NiO plays a vital role in changing the magnitude of electron correlation via the self-energy.

Electronic Structures and Gas-Phase Reactivities of Cationic Late-Transition-Metal Oxides

1994 ◽  
Vol 116 (23) ◽  
pp. 10734-10741 ◽  
Author(s):  
Andreas Fiedler ◽  
Detlef Schroeder ◽  
Sason Shaik ◽  
Helmut Schwarz
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Gas Phase ◽  
Transition Metal Oxides ◽  
Electronic Structures ◽  
Late Transition Metal ◽  
Late Transition

scholarly journals Electret formation in transition metal oxides by electrochemical amorphization

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yong-Jin Kim ◽  
Chan-Ho Yang
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Charge Density ◽  
Electric Fields ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Permanent Magnets ◽  
Underlying Mechanism ◽  
Diffusion Reaction ◽  
Wide Range

AbstractTransition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO3 thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm−2 and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.

High Oxidation State Alkali-Metal Late-Transition-Metal Oxides

2000 ◽  
Vol 658 ◽  
Author(s):  
David B. Currie ◽  
Andrew L. Hector ◽  
Emmanuelle A. Raekelboom ◽  
John R. Owen ◽  
Mark T. Weller
Keyword(s):  
High Pressure ◽  
Solid State ◽  
Transition Metal Oxides ◽  
Late Transition Metal ◽  
High Oxidation State ◽  
Powder Neutron Diffraction ◽  
Nmr Study ◽  
High Oxidation ◽  
Late Transition ◽  
Cation Sites

ABSTRACTLi2NaCu2O4 has been prepared by solid state reaction under high-pressure (250 Atm) oxygen. A structural study, using time-of-flight powder neutron diffraction on a sample made with 7Li, shows a material isostructural with Li3Cu2O4, with sodium occupying the octahedral and lithium the tetrahedral A-cation sites. A 7Li MAS-NMR study of Li3Cu2O4, Li2NaCu2O4 and Li2CuO2 has been used to confirm the Li/Na site ordering.

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