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1. Triangular Arrangement of Ferromagnetic Iron Chains in the High‐ T C Ferromagnet TiFe 1−x Os 2+x B 2

   https://doi.org/10.1002/chem.202201058  

   Scheifers, Jan P. ; Flores, Justin H. ; Janka, Oliver ; Pöttgen, Rainer ; Fokwa, Boniface P. T. ( June 2022 , Chemistry – A European Journal)

   Transition‐metal borides (TMBs) containing B_n‐fragment (n>3) have recently gained interest for their ability to enable exciting magnetic materials. Herein, we show that the B₄‐containing TiFe_0.64(1)Os_2.36(1)B₂is a new ferromagnetic TMB with a Curie temperature of 523(2) K and a Weiss constant of 554(3) K, originating from the chain ofM₃‐triangles (M=64 %Fe+36 %Os). The new phase was synthesized from the elements by arc‐melting, and its structure was elucidated by single‐crystal X‐ray diffraction. It belongs to the Ti_1+xOs_2−xRuB₂‐type structure (space groupP2 m, no. 189) and contains trigonal‐planar B₄boron fragments [B−B distance of 1.87(4) Å] interacting withM₃‐triangles [M–Mdistances of 2.637(8) Å and 3.0199(2) Å]. The experimental results were supported by computational calculations based on the ideal TiFeOs₂B₂composition, which revealed strong ferromagnetic interactions within and between the Fe₃‐triangles. This discovery represents the first magnetically ordered Os‐rich TMB, thus it will help expand our knowledge of the role of Os in low‐dimensional magnetism of intermetallics and enable the design of such materials in the future.

    

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2. Perovskite‐Derived Layered Crystal Structure in SrCo 0.26 Fe 0.74 O 3‐δ Thin Films

   https://doi.org/10.1002/admi.202300807  

   Cho, Eunsoo ; Kumar, Abinash ; Ning, Shuai ; LeBeau, James M. ; Ross, Caroline A. ( January 2024 , Advanced Materials Interfaces)

   Oxygen coordination and vacancy ordering play an important role in dictating the functionality of complex oxides. In this work, an unconventional layering of oxygen ions in a mixed conductor SrCo_1‐xFe_xO_3‐δ(SCFO) thin film grown epitaxially on SrTiO₃(STO) is reported. Scanning transmission electron microscopy (STEM) reveals alternating layers of oxygen deficiency along the growth direction, with the oxygen‐rich layer correlated with the neighboring Co,Fe‐site intensity, and contraction of the Sr–Sr distance. Density functional theory (DFT) calculations and STEM image simulations support the emergence of periodic (Co,Fe)O₆and (Co,Fe)O₄/(Co,Fe)O₅layers, an ordering that is also sensitive to the Co:Fe ratio.

    

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3. Solvothermal Synthesis of [Cr 7 S 8 (en) 8 Cl 2 ]Cl 3  ⋅ 2H 2 O with Magnetically Frustrated [Cr 7 S 8 ] 5+ Double‐Cubes**

   https://doi.org/10.1002/chem.202103761  

   Gamage, Eranga H. ; Clark, Judith K. ; Yazback, Maher ; Cheng, Hai‐Ping ; Shatruk, Michael ; Kovnir, Kirill ( December 2021 , Chemistry – A European Journal)

   A novel transition metal chalcohalide [Cr₇S₈(en)₈Cl₂]Cl₃ ⋅ 2H₂O, with [Cr₇S₈]⁵⁺dicubane cationic clusters, has been synthesized by a low temperature solvothermal method, using dimethyl sulfoxide (DMSO) and ethylenediamine (en) solvents. Ethylenediamine ligand exhibits bi‐ and monodentate coordination modes; in the latter case ethylenediamine coordinates to Cr atoms of adjacent clusters, giving rise to a 2D polymeric structure. Although magnetic susceptibility shows no magnetic ordering down to 1.8 K, a highly negative Weiss constant,θ=−224(2) K, obtained from Curie‐Weiss fit of inverse susceptibility, suggests strong antiferromagnetic (AFM) interactions betweenS=3/2 Cr(III) centers. Due to the complexity of the system with (2S+1)⁷=16384 microstates from seven Cr³⁺centers, a simplified model with only two exchange constants was used for simulations. Density‐functional theory (DFT) calculations yielded the two exchange constants to beJ₁=−21.4 cm⁻¹andJ₂=−30.2 cm⁻¹, confirming competing AFM coupling between the shared Cr³⁺center and the peripheral Cr³⁺ions of the dicubane cluster. The best simulation of the experimental data was obtained withJ₁=−20.0 cm⁻¹andJ₂=−21.0 cm⁻¹, in agreement with the slightly stronger AFM exchange within the triangles of the peripheral Cr³⁺ions as compared to the AFM exchange between the central and peripheral Cr³⁺ions. This compound is proposed as a synthon towards magnetically frustrated systems assembled by linking dicubane transition metal‐chalcogenide clusters into polymeric networks.

    

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4. Strong Damping‐Like Spin‐Orbit Torque and Tunable Dzyaloshinskii–Moriya Interaction Generated by Low‐Resistivity Pd 1− x Pt x Alloys

   https://doi.org/10.1002/adfm.201805822  

   Zhu, Lijun ; Sobotkiewich, Kemal ; Ma, Xin ; Li, Xiaoqin ; Ralph, Daniel C. ; Buhrman, Robert A. ( February 2019 , Advanced Functional Materials)

   Despite their great promise for providing a pathway for very efficient and fast manipulation of magnetization, spin‐orbit torque (SOT) operations are currently energy inefficient due to a low damping‐like SOT efficiency per unit current bias, and/or the very high resistivity of the spin Hall materials. This work reports an advantageous spin Hall material, Pd_1−xPt_x, which combines a low resistivity with a giant spin Hall effect as evidenced with three independent SOT ferromagnetic detectors. The optimal Pd_0.25Pt_0.75alloy has a giant internal spin Hall ratio of >0.60 (damping‐like SOT efficiency of ≈0.26 for all three ferromagnets) and a low resistivity of ≈57.5 µΩ cm at a 4 nm thickness. Moreover, it is found that the Dzyaloshinskii–Moriya interaction (DMI), the key ingredient for the manipulation of chiral spin arrangements (e.g., magnetic skyrmions and chiral domain walls), is considerably strong at the Pd_1−xPt_x/Fe_0.6Co_0.2B_0.2interface when compared to that at Ta/Fe_0.6Co_0.2B_0.2or W/Fe_0.6Co_0.2B_0.2interfaces and can be tuned by a factor of 5 through control of the interfacial spin‐orbital coupling via the heavy metal composition. This work establishes a very effective spin current generator that combines a notably high energy efficiency with a very strong and tunable DMI for advanced chiral spintronics and spin torque applications.

    

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5. Effect of R-site element on crystalline phase and thermal stability of Fe substituted Mn mullite-type oxides: R 2 (Mn 1−x Fe x ) 4 O 10−δ (R = Y, Sm or Bi; x = 0, 0.5, 1)

   https://doi.org/10.1039/C7RA09699B  

   Thampy, Sampreetha ; Ashburn, Nickolas ; Martin, Thomas J. ; Li, Chenzhe ; Zheng, Yongping ; Chan, Julia Y. ; Cho, Kyeongjae ; Hsu, Julia W. ( January 2018 , RSC Advances)

   Combining experimental and theoretical studies, we investigate the role of R-site (R = Y, Sm, Bi) element on the phase formation and thermal stability of R 2 (Mn 1−x Fe x ) 4 O 10−δ ( x = 0, 0.5, 1) mullite-type oxides. Our results show a distinct R-site dependent phase behavior for mullite-type oxides as Fe is substituted for Mn: 100% mullite-type phase was formed in (Y, Sm, Bi) 2 Mn 4 O 10 ; 55% and 18% of (Y, Sm) 2 Mn 2 Fe 2 O 10−δ was found when R = Y and Sm, respectively, for equal Fe and Mn molar concentrations in the reactants, whereas Bi formed 54% O10- and 42% O9-mixed mullite-type phases. Furthermore, when the reactants contain 100% Fe, no mullite-type phase was formed for R = Y and Sm, but a sub-group transition to Bi 2 Fe 4 O 9 O9-phase was found for R = Bi. Thermogravimetric analysis and density functional theory (DFT) calculation results show a decreasing thermal stability in O10-type structure with increasing Fe incorporation; for example, the decomposition temperature is 1142 K for Bi 2 Mn 2 Fe 2 O 10−δ vs. 1217 K for Bi 2 Mn 4 O 10 . On the other hand, Bi 2 Fe 4 O 9 O9-type structure is found to be thermally stable up to 1227 K. These findings are explained by electronic structure calculations: (1) as Fe concentration increases, Jahn–Teller distortion results in mid band-gap empty states from unstable Fe 4+ occupied octahedra, which is responsible for the decrease in O10 structure stability; (2) the directional sp orbital hybridization unique to Bi effectively stabilizes the mullite-type structure as Fe replaces Mn. 

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