| 1. |
- Ehrler, Jonathan, et al.
(författare)
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Magneto-structural correlations in a systematically disordered B2 lattice
- 2020
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Ingår i: New Journal of Physics. - : IOP PUBLISHING LTD. - 1367-2630. ; 22:7
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Tidskriftsartikel (refereegranskat)abstract
- Ferromagnetism in certain B2 ordered alloys such as Fe(60)Al(40)can be switched on, and tuned, via antisite disordering of the atomic arrangement. The disordering is accompanied by a similar to 1 % increase in the lattice parameter. Here we performed a systematic disordering of B2 Fe(60)Al(40)thin films, and obtained correlations between the order parameter (S), lattice parameter (a(0)), and the induced saturation magnetization (M-s). As the lattice is gradually disordered, a critical point occurs at 1 -S= 0.6 anda(0)= 2.91 angstrom, where a sharp increase of theM(s)is observed. DFT calculations suggest that below the critical point the system magnetically behaves as it would still be fully ordered, whereas above, it is largely the increase ofa(0)in the disordered state that determines theM(s). The insights obtained here can be useful for achieving tailored magnetic properties in alloys through disordering.
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| 2. |
- Huang, Xing, et al.
(författare)
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Semiconducting Conjugated Coordination Polymer with High Charge Mobility Enabled by "4+2" Phenyl Ligands
- 2023
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 145:4, s. 2430-2438
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Tidskriftsartikel (refereegranskat)abstract
- Electrically conductive coordination polymers and metal-organic frameworks are attractive emerging electroactive materials for (opto-)electronics. However, developing semiconducting coordination polymers with high charge carrier mobility for devices remains a major challenge, urgently requiring the rational design of ligands and topological networks with desired electronic structures. Herein, we demonstrate a strategy for synthesizing high-mobility semiconducting conjugated coordination polymers (c-CPs) utilizing novel conjugated ligands with D2h symmetry, namely, "4 + 2" phenyl ligands. Compared with the conventional phenyl ligands with C6h symmetry, the reduced symmetry of the "4 + 2" ligands leads to anisotropic coordination in the formation of c-CPs. Consequently, we successfully achieve a single-crystalline three-dimensional (3D) c-CP Cu4DHTTB (DHTTB = 2,5-dihydroxy-1,3,4,6-tetrathiolbenzene), containing orthogonal ribbon-like pi-d conjugated chains rather than 2D conjugated layers. DFT calculation suggests that the resulting Cu4DHTTB exhibits a small band gap (similar to 0.2 eV), strongly dispersive energy bands near the Fermi level with a low electron-hole reduced effective mass (similar to 0.2m0*). Furthermore, the four-probe method reveals a semiconducting behavior with a decent conductivity of 0.2 S/cm. Thermopower measurement suggests that it is a p-type semiconductor. Ultrafast terahertz photoconductivity measurements confirm Cu4DHTTB's semiconducting nature and demonstrate the Drude-type transport with high charge carrier mobilities up to 88 +/- 15 cm2 V-1 s-1, outperforming the conductive 3D coordination polymers reported till date. This molecular design strategy for constructing high-mobility semiconducting c-CPs lays the foundation for achieving high-performance c-CP-based (opto-)electronics.
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| 3. |
- Iurchuk, Vadym, et al.
(författare)
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All-Electrical Operation of a Curie Switch at Room Temperature
- 2023
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Ingår i: Physical Review Applied. - : American Physical Society (APS). - 2331-7019. ; 20:2
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Tidskriftsartikel (refereegranskat)abstract
- We present all-electrical operation of a FexCr1-x-based Curie switch at room temperature. More specifically, we study the current-induced thermally driven transition from ferromagnetic to antiferromagnetic Magnetometry measurements at different temperatures show that the transition from the ferromagnetic to the antiferromagnetic coupling at zero field is observed at approximately 325 K. Analytical modeling confirms that the observed temperature-dependent transition from indirect ferromagnetic to indirect antiferromagnetic interlayer exchange coupling originates from the modification of the effective interlayer exchange constant through the ferromagnetic-to-paramagnetic transition in the Fe17.5Cr82.5 spacer with minor contributions from the thermally driven variations of the magnetization and magnetic anisotropy of the Fe layers. Room-temperature current-in-plane magnetotransport measurements on the patterned Fe/Cr/Fe17.5Cr82.5/Cr/Fe strips show the transition from the "low-resistance" parallel to the "highresistance" antiparallel remanent magnetization configuration, upon increased probing current density. Quantitative comparison of the switching fields, obtained by magnetometry and magnetotransport, confirms that the Joule heating is the main mechanism responsible for the observed current-induced resistive switching.
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| 4. |
- Lu, Yang, et al.
(författare)
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Precise tuning of interlayer electronic coupling in layered conductive metal-organic frameworks
- 2022
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Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Layered metal-organic frameworks attract interests for optoelectronics and spintronics. Here, the authors report a strategy to tune interlayer charge transport and thermoelectric properties via side-chain induced control of the layer spacing. Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have attracted increasing interests for (opto)-electronics and spintronics. They generally consist of van der Waals stacked layers and exhibit layer-depended electronic properties. While considerable efforts have been made to regulate the charge transport within a layer, precise control of electronic coupling between layers has not yet been achieved. Herein, we report a strategy to precisely tune interlayer charge transport in 2D c-MOFs via side-chain induced control of the layer spacing. We design hexaiminotriindole ligands allowing programmed functionalization with tailored alkyl chains (HATI_CX, X = 1,3,4; X refers to the carbon numbers of the alkyl chains) for the synthesis of semiconducting Ni-3(HATI_CX)(2). The layer spacing of these MOFs can be precisely varied from 3.40 to 3.70 angstrom, leading to widened band gap, suppressed carrier mobilities, and significant improvement of the Seebeck coefficient. With this demonstration, we further achieve a record-high thermoelectric power factor of 68 +/- 3 nW m(-1) K-2 in Ni-3(HATI_C3)(2), superior to the reported holes-dominated MOFs.
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| 5. |
- Zhuang, Kejia, et al.
(författare)
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Numerical investigation of sequential cuts residual stress considering tool edge radius in machining of AISI 304 stainless steel
- 2022
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Ingår i: Simulation Modelling Practice and Theory. - : Elsevier BV. - 1569-190X. ; 118
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Tidskriftsartikel (refereegranskat)abstract
- Residual stress affects component performance, and the existence of pre-stress changes the residual stress of machined surfaces as well, emphasizing the importance of studying the evolution of residual stress in sequential cutting. This paper reports a numerical investigation of the machining-induced residual stress profile of sequential cuts for orthogonal cutting of AISI 304, considering the effects of edge radius and cutting depth. A Coupled Eulerian-Lagrangian (CEL) model is employed for the first time to stably simulate the evolution of residual stress of multiple sequential cuts. The effectiveness of the proposed method is verified by comparing the chip formation and surface residual stress between simulated and experimental results. The cutting force and cutting temperature, as well as mechanical and thermal loads, are extracted to explain the generation and evolution of residual stress in sequential cutting. It is found that the residual stress on the machined surfaces will decrease during sequential cutting, and a stable value can be reached after approximately six sequential cuts. With the progress of sequential cutting, a larger honed tool edge radius and cutting depth will lead to a slower reduction of residual stress.
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