Field-tunable toroidal moment in a chiral-lattice magnet

AbstractFerrotoroidal order, which represents a spontaneous arrangement of toroidal moments, has recently been found in a few linear magnetoelectric materials. However, tuning toroidal moments in these materials is challenging. Here, we report switching between ferritoroidal and ferrotoroidal phases by a small magnetic field, in a chiral triangular-lattice magnet BaCoSiO4 with tri-spin vortices. Upon applying a magnetic field, we observe multi-stair metamagnetic transitions, characterized by equidistant steps in the net magnetic and toroidal moments. This highly unusual ferri-ferroic order appears to come as a result of an unusual hierarchy of frustrated isotropic exchange couplings revealed by first principle calculations, and the antisymmetric exchange interactions driven by the structural chirality. In contrast to the previously known toroidal materials identified via a linear magnetoelectric effect, BaCoSiO4 is a qualitatively new multiferroic with an unusual coupling between several different orders, and opens up new avenues for realizing easily tunable toroidal orders.

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Investigations on Forming Ether Coated Iron Nanoparticle Materials by First-Principle Calculations and Molecular Dynamic Simulations

Coatings ◽

10.3390/coatings9060395 ◽

2019 ◽

Vol 9 (6) ◽

pp. 395 ◽

Cited By ~ 1

Author(s):

Junlei Sun ◽

Shixuan Hui ◽

Pingan Liu ◽

Ruochen Sun ◽

Mengjun Wang

Keyword(s):

Molecular Dynamic ◽

Md Simulations ◽

First Principle ◽

Sphere Model ◽

Dynamic Simulations ◽

First Principle Calculations ◽

Binding Force ◽

Adsorption Behaviors ◽

Single Sphere ◽

To Come

The mechanism of coating effects between ether molecules and iron (Fe) nanoparticles was generally estimated using first-principle calculations and molecular dynamic (MD) simulations coupling with Fe (110) crystal layers and sphere models. In the present work, the optimized adsorption site and its energy were confirmed. The single sphere model in MD simulations was studied for typical adsorption behaviors, and the double sphere model was built to be more focused on the gap impact between two particles. In those obtained results, it is demonstrated that ether molecules were prone to be adsorbed on the long bridge site of the Fe (110) crystal while comparing with other potential sites. Although the coating was not completely uniform at early stages, the formation of ether layer ended up being equilibrated finally. Accompanied with charge transfer, those coated ether molecules exerted much binding force on the shell Fe atoms. Additionally, when free ether molecules were close to the gap between two nanoparticles, they were found to come under double adsorption effects. Although this effect might not be sufficient to keep them adsorbed, the movement of these ether molecules were hindered to some extent.

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High-temperature oxidation behavior of CVD-SiC ceramic coating in wet oxygen and structural evolution of oxidation product: Experiment and first-principle calculations

Applied Surface Science ◽

10.1016/j.apsusc.2021.149808 ◽

2021 ◽

Vol 556 ◽

pp. 149808

Author(s):

Pengfei Zhang ◽

Yulei Zhang ◽

Guohui Chen ◽

Wenhan Gai ◽

Jingan Kong

Keyword(s):

High Temperature ◽

High Temperature Oxidation ◽

Oxidation Behavior ◽

Ceramic Coating ◽

Structural Evolution ◽

First Principle ◽

Temperature Oxidation ◽

First Principle Calculations ◽

Sic Ceramic ◽

High Temperature Oxidation Behavior

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A First-Principle Study of Monolayer Transition Metal Carbon Trichalcogenides

Journal of Superconductivity and Novel Magnetism ◽

10.1007/s10948-021-05980-1 ◽

2021 ◽

Author(s):

Muhammad Yar Khan ◽

Yan Liu ◽

Tao Wang ◽

Hu Long ◽

Miaogen Chen ◽

...

Keyword(s):

Phonon Dispersion ◽

Magnetic Ordering ◽

Dimensional Structure ◽

First Principle ◽

Two Dimensional ◽

Biaxial Strain ◽

Half Metallic ◽

First Principle Calculations ◽

Potential Applications ◽

External Strain

AbstractMonolayer MnCX3 metal–carbon trichalcogenides have been investigated by using the first-principle calculations. The compounds show half-metallic ferromagnetic characters. Our results reveal that their electronic and magnetic properties can be altered by applying uniaxial or biaxial strain. By tuning the strength of the external strain, the electronic bandgap and magnetic ordering of the compounds change and result in a phase transition from the half-metallic to the semiconducting phase. Furthermore, the vibrational and thermodynamic stability of the two-dimensional structure has been verified by calculating the phonon dispersion and molecular dynamics. Our study paves guidance for the potential applications of these two mono-layers in the future for spintronics and straintronics devices.

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Phase transitions in the Heisenberg model on a layered triangular lattice in a magnetic field

Phase Transitions ◽

10.1080/01411594.2021.1938047 ◽

2021 ◽

pp. 1-10

Author(s):

Akai Murtazaev ◽

Magomedzagir Badiev ◽

Magomedsheykh Ramazanov ◽

Magomed Magomedov

Keyword(s):

Magnetic Field ◽

Phase Transitions ◽

Triangular Lattice ◽

Heisenberg Model

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Isotropic Nature of the Metallic Kagome Ferromagnet Fe3Sn2 at High Temperatures

Crystals ◽

10.3390/cryst11030307 ◽

2021 ◽

Vol 11 (3) ◽

pp. 307

Author(s):

Rebecca L. Dally ◽

Daniel Phelan ◽

Nicholas Bishop ◽

Nirmal J. Ghimire ◽

Jeffrey W. Lynn

Keyword(s):

Elevated Temperatures ◽

Magnetocrystalline Anisotropy ◽

Inelastic Neutron Scattering ◽

Exchange Interactions ◽

Inelastic Neutron ◽

Temperature Threshold ◽

Magnetic Exchange ◽

Spatial Anisotropy ◽

Isotropic Exchange ◽

State Spin

Anisotropy and competing exchange interactions have emerged as two central ingredients needed for centrosymmetric materials to exhibit topological spin textures. Fe3Sn2 is thought to have these ingredients as well, as it has recently been discovered to host room temperature skyrmionic bubbles with an accompanying topological Hall effect. We present small-angle inelastic neutron scattering measurements that unambiguously show that Fe3Sn2 is an isotropic ferromagnet below TC≈660 K to at least 480 K—the lower temperature threshold of our experimental configuration. Fe3Sn2 is known to have competing magnetic exchange interactions, correlated electron behavior, weak magnetocrystalline anisotropy, and lattice (spatial) anisotropy; all of these features are thought to play a role in stabilizing skyrmions in centrosymmetric systems. Our results reveal that at the elevated temperatures measured, there is an absence of significant magnetocrystalline anisotropy and that the system behaves as a nearly ideal isotropic exchange interaction ferromagnet, with a spin stiffness D(T=480 K)=168 meV Å2, which extrapolates to a ground state spin stiffness D(T=0 K)=231 meV Å2.

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Monolayer 1T and 1T′ MoSO as Promising Electrocatalyst for Hydrogen Evolution based on First Principle Calculations

ChemPhysChem ◽

10.1002/cphc.202100038 ◽

2021 ◽

Author(s):

Feifei Li ◽

Ziping Niu ◽

Lixin Zhang

Keyword(s):

Hydrogen Evolution ◽

First Principle ◽

First Principle Calculations

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Quantitative Evaluations of Hydrogen Diffusivity in V-X (X = Cr, Al, Pd) Alloy Membranes Based on Hydrogen Chemical Potential

Membranes ◽

10.3390/membranes11010067 ◽

2021 ◽

Vol 11 (1) ◽

pp. 67

Author(s):

Asuka Suzuki ◽

Hiroshi Yukawa

Keyword(s):

Nearest Neighbor ◽

Chemical Potential ◽

Hydrogen Permeability ◽

First Principle ◽

Hydrogen Diffusivity ◽

Hydrogen Atoms ◽

First Principle Calculations ◽

Blocking Effects ◽

Pd Alloy ◽

Quantitative Evaluations

Vanadium (V) has higher hydrogen permeability than Pd-based alloy membranes but exhibits poor resistance to hydrogen-induced embrittlement. The alloy elements are added to reduce hydrogen solubility and prevent hydrogen-induced embrittlement. To enhance hydrogen permeability, the alloy elements which improve hydrogen diffusivity in V are more suitable. In the present study, hydrogen diffusivity in V-Cr, V-Al, and V-Pd alloy membranes was investigated in view of the hydrogen chemical potential and compared with the previously reported results of V-Fe alloy membranes. The additions of Cr and Fe to V improved the mobility of hydrogen atoms. In contrast, those of Al and Pd decreased hydrogen diffusivity. The first principle calculations revealed that the hydrogen atoms cannot occupy the first-nearest neighbor T sites (T1 sites) of Al and Pd in the V crystal lattice. These blocking effects will be a dominant contributor to decreasing hydrogen diffusivity by the additions of Al and Pd. For V-based alloy membranes, Fe and Cr are more suitable alloy elements compared with Al and Pd in view of hydrogen diffusivity.

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Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

Scientific Reports ◽

10.1038/s41598-020-78598-3 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Durga Sankar Vavilapalli ◽

Ambrose A. Melvin ◽

F. Bellarmine ◽

Ramanjaneyulu Mannam ◽

Srihari Velaga ◽

...

Keyword(s):

Single Crystal ◽

Single Crystals ◽

Photoelectron Spectroscopy ◽

Diffraction Method ◽

Lattice Parameter ◽

First Principle ◽

X Ray Diffraction ◽

X Ray ◽

First Principle Calculations ◽

Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

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Author Correction: Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

Scientific Reports ◽

10.1038/s41598-021-85663-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Durga Sankar Vavilapalli ◽

Ambrose A. Melvin ◽

F. Bellarmine ◽

Ramanjaneyulu Mannam ◽

Srihari Velaga ◽

...

Keyword(s):

Single Crystals ◽

First Principle ◽

First Principle Calculations

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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The thermal stability of FAPbBr3 nanocrystals from temperature-dependent photoluminescence and first-principles calculations

RSC Advances ◽

10.1039/d0ra07668f ◽

2020 ◽

Vol 10 (72) ◽

pp. 44373-44381

Author(s):

Xiaozhe Wang ◽

Qi Wang ◽

Zhijun Chai ◽

Wenzhi Wu

Keyword(s):

First Principles ◽

First Principle ◽

First Principles Calculations ◽

Temperature Dependent ◽

Time Resolved ◽

First Principle Calculations ◽

Steady State Time ◽

Time Resolved Photoluminescence ◽

Thermal Stability Of ◽

Temperature Dependent Photoluminescence

The thermal properties of FAPbBr3 perovskite nanocrystals (PNCs) is investigated by use of temperature-dependent steady-state/time-resolved photoluminescence and first-principle calculations.

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