scholarly journals Reversal of the magnetoelectric effect at a ferromagnetic metal/ferroelectric interface induced by metal oxidation

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhaojin Chen ◽  
Qiong Yang ◽  
Lingling Tao ◽  
Evgeny Y. Tsymbal
Keyword(s):  
Electric Fields ◽  
Density Functional ◽  
Magnetoelectric Effect ◽  
Density Functional Theory Calculations ◽  
Magnetoelectric Coupling ◽  
Oxygen Stoichiometry ◽  
Functional Theory ◽  
Ferromagnetic Metals ◽  
Multiferroic Heterostructures ◽  
Silicon Based

AbstractMultiferroic materials composed of ferromagnetic and ferroelectric components are interesting for technological applications due to sizable magnetoelectric coupling allowing the control of magnetic properties by electric fields. Due to being compatible with the silicon-based technology, HfO2-based ferroelectrics could serve as a promising component in the composite multiferroics. Recently, a strong charge-mediated magnetoelectric coupling has been predicted for a Ni/HfO2 multiferroic heterostructure. Here, using density functional theory calculations, we systematically study the effects of the interfacial oxygen stoichiometry relevant to experiments on the magnetoelectric effect at the Ni/HfO2 interface. We demonstrate that the magnetoelectric effect is very sensitive to the interface stoichiometry and is reversed if an oxidized Ni monolayer is formed at the interface. The reversal of the magnetoelectric effect is driven by a strong Ni−O bonding producing exchange-split polarization-sensitive antibonding states at the Fermi energy. We argue that the predicted reversal of the magnetoelectric effect is typical for other 3d ferromagnetic metals, such as Co and Fe, where the metal-oxide antibonding states have an opposite spin polarization compared to that in the pristine ferromagnetic metals. Our results provide an important insight into the mechanism of the interfacial magnetoelectric coupling, which is essential for the physics and application of multiferroic heterostructures.

Exceptional mechano-electronic properties in the HfN2 monolayer: a promising candidate in low-power flexible electronics, memory devices and photocatalysis

2020 ◽  
Vol 22 (37) ◽  
pp. 21275-21287 ◽  
Author(s):  
Manish Kumar Mohanta ◽  
I. S. Fathima ◽  
Abir De Sarkar
Keyword(s):  
Density Functional Theory ◽  
Low Power ◽  
Electronic Properties ◽  
Electric Fields ◽  
Flexible Electronics ◽  
Density Functional ◽  
External Perturbation ◽  
Density Functional Theory Calculations ◽  
Promising Candidate ◽  
Functional Theory

The response of the electronic properties of the HfN2 monolayer to external perturbation such as strain and electric fields has been investigated using density functional theory calculations for its device-based applications and photocatalysis.

scholarly journals Strategies for Red-Shifting Type I Photoinitiators: Internal Electric Fields versus Lewis Acids versus Increasing Conjugation

2019 ◽  
Vol 72 (8) ◽  
pp. 627 ◽  
Author(s):  
Nicholas S. Hill ◽  
Michelle L. Coote
Keyword(s):  
Excited States ◽  
Electric Fields ◽  
Lewis Acids ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Water Soluble ◽  
Type I ◽  
Internal Electric Field ◽  
Functional Theory ◽  
Derivatives Of

Time-dependent density functional theory calculations were performed on derivatives of Irgacure 2959, a water-soluble, acetophenone-type photoinitiator, in order to assess the relative merits and drawbacks of three distinct ways of modifying its photochemistry: Lewis acid complexation, changing the amount of conjugation in the molecule, and application of an internal electric field through inclusion of a remote charged functional group. The effectiveness of each of the three methods was evaluated against the magnitude of the change in energy of the excited states. Internal electric fields were shown to provide the best method for targeting specific excited states in a controlled and rational manner. The other strategies also had significant effects but it was more difficult to independently target different transitions. Nonetheless, for the specific case of Irgacure 2959, we predict that its complexation with Mg2+ ions in a range of solvents will both red-shift the initiator’s absorbance while improving its efficiency and it is thus a promising candidate for testing as a visible light photoinitiator.

scholarly journals Strain vs. charge mediated magnetoelectric coupling across the magnetic oxide/ferroelectric interfaces

RSC Advances ◽  
2019 ◽  
Vol 9 (23) ◽  
pp. 13033-13041 ◽  
Author(s):  
Binod Paudel ◽  
Igor Vasiliev ◽  
Mahmoud Hammouri ◽  
Dmitry Karpov ◽  
Aiping Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Magnetoelectric Coupling ◽  
Neutron Reflectometry ◽  
Magnetic Oxide ◽  
Functional Theory ◽  
Polarized Neutron ◽  
Polarized Neutron Reflectometry

We utilize polarized neutron reflectometry in consort with ab initio based density functional theory calculations to study interface magnetoelectric coupling across a ferroelectric PbZr0.2Ti0.8O3 and magnetic La0.67Sr0.33MnO3 heterostructure.

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

A New Interpretation of the Structure and Solvent Dependence of the Far UV Circular Dichroism Spectrum of Short Oligopeptides

2019 ◽  
Author(s):  
Anshuman Kumar ◽  
Reinhard Schweitzer-Stenner ◽  
Bryan Wong
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Cd Spectra ◽  
Functional Theory ◽  
Polyproline Ii ◽  
Solvent Dependence ◽  
Explicit Consideration ◽  
New Interpretation ◽  
Implicit And Explicit ◽  
Explicit Water

In this work, we carry out new time-dependent density functional theory calculations on the cationic tripeptide GAG in implicit and explicit water to determine the transitions that give rise to the observed CD signals of polyproline II and β-strand conformations. Our results reveal a plethora of electronic transitions that are governed by configurational interactions between multiple molecular orbital transitions of comparable energy. We also show that reproducing the CD spectra of polyproline II and β-strand conformations requires the explicit consideration of water molecules. The structure dependence of delocalized occupied orbitals contributes to the experimentally-observed invalidation of Flory’s isolated pair hypothesis.

A New Interpretation of the Structure and Solvent Dependence of the Far UV Circular Dichroism Spectrum of Short Oligopeptides

2019 ◽  
Author(s):  
Anshuman Kumar ◽  
Reinhard Schweitzer-Stenner ◽  
Bryan Wong
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Cd Spectra ◽  
Functional Theory ◽  
Polyproline Ii ◽  
Solvent Dependence ◽  
Explicit Consideration ◽  
New Interpretation ◽  
Implicit And Explicit ◽  
Explicit Water

In this work, we carry out new time-dependent density functional theory calculations on the cationic tripeptide GAG in implicit and explicit water to determine the transitions that give rise to the observed CD signals of polyproline II and β-strand conformations. Our results reveal a plethora of electronic transitions that are governed by configurational interactions between multiple molecular orbital transitions of comparable energy. We also show that reproducing the CD spectra of polyproline II and β-strand conformations requires the explicit consideration of water molecules. The structure dependence of delocalized occupied orbitals contributes to the experimentally-observed invalidation of Flory’s isolated pair hypothesis.

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

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