scholarly journals Alloying effect on the order–disorder transformation in tetragonal FeNi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li-Yun Tian ◽  
Oliver Gutfleisch ◽  
Olle Eriksson ◽  
Levente Vitos
Keyword(s):  
Transition Temperature ◽  
High Performance ◽  
Density Functional ◽  
Permanent Magnets ◽  
Positive Impact ◽  
Design Strategies ◽  
Alloying Effect ◽  
Functional Theory ◽  
Disorder Transition ◽  
Disorder Transition Temperature

AbstractTetragonal ($${\hbox{L1}}_{0}$$ L1 0 ) FeNi is a promising material for high-performance rare-earth-free permanent magnets. Pure tetragonal FeNi is very difficult to synthesize due to its low chemical order–disorder transition temperature ($$\approx {593}$$ ≈ 593  K), and thus one must consider alternative non-equilibrium processing routes and alloy design strategies that make the formation of tetragonal FeNi feasible. In this paper, we investigate by density functional theory as implemented in the exact muffin-tin orbitals method whether alloying FeNi with a suitable element can have a positive impact on the phase formation and ordering properties while largely maintaining its attractive intrinsic magnetic properties. We find that small amount of non-magnetic (Al and Ti) or magnetic (Cr and Co) elements increase the order–disorder transition temperature. Adding Mo to the Co-doped system further enhances the ordering temperature while the Curie temperature is decreased only by a few degrees. Our results show that alloying is a viable route to stabilizing the ordered tetragonal phase of FeNi.

scholarly journals Strain Investigation on Spin-Dependent Transport Properties of γ-Graphyne Nanoribbon Between Gold Electrodes

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yun Li ◽  
Xiaobo Li ◽  
Shidong Zhang ◽  
Liemao Cao ◽  
Fangping Ouyang ◽  
...  
Keyword(s):  
Transport Properties ◽  
High Performance ◽  
Density Functional ◽  
Strain Engineering ◽  
Molecular Junctions ◽  
Spin Splitting ◽  
Functional Theory ◽  
Spin Dependent Transport ◽  
The Density Functional Theory ◽  
Dependent Transport

AbstractStrain engineering has become one of the effective methods to tune the electronic structures of materials, which can be introduced into the molecular junction to induce some unique physical effects. The various γ-graphyne nanoribbons (γ-GYNRs) embedded between gold (Au) electrodes with strain controlling have been designed, involving the calculation of the spin-dependent transport properties by employing the density functional theory. Our calculated results exhibit that the presence of strain has a great effect on transport properties of molecular junctions, which can obviously enhance the coupling between the γ-GYNR and Au electrodes. We find that the current flowing through the strained nanojunction is larger than that of the unstrained one. What is more, the length and strained shape of the γ-GYNR serves as the important factors which affect the transport properties of molecular junctions. Simultaneously, the phenomenon of spin-splitting occurs after introducing strain into nanojunction, implying that strain engineering may be a new means to regulate the electron spin. Our work can provide theoretical basis for designing of high performance graphyne-based devices in the future.

Increased Order–Disorder Transition Temperature for a Rod–Coil Block Copolymer in the Presence of a Magnetic Field

2011 ◽  
Vol 44 (19) ◽  
pp. 7503-7507 ◽  
Author(s):  
Bryan McCulloch ◽  
Giuseppe Portale ◽  
Wim Bras ◽  
Rachel A. Segalman
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Block Copolymer ◽  
Disorder Transition ◽  
Disorder Transition Temperature

Experimental and density functional theory investigation of Pt-loaded titanium dioxide/molybdenum disulfide nanohybrid for SO2 gas sensing

2019 ◽  
Vol 43 (12) ◽  
pp. 4900-4907 ◽  
Author(s):  
Dongzhi Zhang ◽  
Maosong Pang ◽  
Junfeng Wu ◽  
Yuhua Cao
Keyword(s):  
Density Functional Theory ◽  
Titanium Dioxide ◽  
Molybdenum Disulfide ◽  
Self Assembly ◽  
High Performance ◽  
Density Functional ◽  
Gas Sensing ◽  
Layer By Layer ◽  
Functional Theory ◽  
So2 Gas

A high-performance sulfur dioxide sensor based on a platinum-loaded titanium dioxide/molybdenum disulfide ternary nanocomposite is synthesized via layer-by-layer self-assembly.

scholarly journals Higher superconducting transition temperature by breaking the universal pressure relation

2019 ◽  
Vol 116 (6) ◽  
pp. 2004-2008 ◽  
Author(s):  
Liangzi Deng ◽  
Yongping Zheng ◽  
Zheng Wu ◽  
Shuyuan Huyan ◽  
Hung-Cheng Wu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Temperature ◽  
Transition Temperature ◽  
Density Functional ◽  
High Temperature Superconductors ◽  
Density Functional Theory Calculations ◽  
Universal Relation ◽  
Superconducting Transition ◽  
Functional Theory ◽  
A Charge

By investigating the bulk superconducting state via dc magnetization measurements, we have discovered a common resurgence of the superconducting transition temperatures (Tcs) of the monolayer Bi2Sr2CuO6+δ(Bi2201) and bilayer Bi2Sr2CaCu2O8+δ(Bi2212) to beyond the maximum Tcs (Tc-maxs) predicted by the universal relation between Tcand doping (p) or pressure (P) at higher pressures. The Tcof underdoped Bi2201 initially increases from 9.6 K at ambient to a peak at 23 K at 26 GPa and then drops as expected from the universal Tc-P relation. However, at pressures above 40 GPa, Tcrises rapidly without any sign of saturation up to 30 K at 51 GPa. Similarly, the Tcfor the slightly overdoped Bi2212 increases after passing a broad valley between 20 and 36 GPa and reaches 90 K without any sign of saturation at 56 GPa. We have, therefore, attributed this Tcresurgence to a possible pressure-induced electronic transition in the cuprate compounds due to a charge transfer between the Cu 3dx2−y2and the O 2pbands projected from a hybrid bonding state, leading to an increase of the density of states at the Fermi level, in agreement with our density functional theory calculations. Similar Tc-P behavior has also been reported in the trilayer Br2Sr2Ca2Cu3O10+δ(Bi2223). These observations suggest that higher Tcs than those previously reported for the layered cuprate high-temperature superconductors can be achieved by breaking away from the universal Tc-P relation through the application of higher pressures.

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