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Full-Text Articles in Engineering
Pressure Induced Magneto-Structural Phase Transitions In Layered Rmn2x2 Compounds (Invited), Shane Kennedy, Jianli Wang, Stewart Campbell, Michael Hofmann, S X. Dou
Pressure Induced Magneto-Structural Phase Transitions In Layered Rmn2x2 Compounds (Invited), Shane Kennedy, Jianli Wang, Stewart Campbell, Michael Hofmann, S X. Dou
Shi Xue Dou
We have studied a range of pseudo-ternaries derived from the parent compound PrMn2 Ge 2, substituting for each constituent element with a smaller one to contract the lattice. This enables us to observe the magneto-elastic transitions that occur as the Mn-Mn nearest neighbour distance is reduced and to assess the role of Pr on the magnetism. Here, we report on the PrMn2 Ge 2−xSix, Pr1−xYxMn2 Ge 2, and PrMn2−xFex Ge 2 systems. The pressure produced by chemical substitution in these pseudo-ternaries is inherently non-uniform, with local pressure variations dependent on the local atomic distribution. We find that concentrated chemical substitution …
Magnetic Transitions In Lafe13-X-Ycoysix Compounds, Jianli Wang, S J. Campbell, S J. Kennedy, P Shamba, R Zeng, S X. Dou, G H. Wu
Magnetic Transitions In Lafe13-X-Ycoysix Compounds, Jianli Wang, S J. Campbell, S J. Kennedy, P Shamba, R Zeng, S X. Dou, G H. Wu
Shi Xue Dou
The magnetic properties of a set of LaFe13−x−yCoySix compounds (x = 1.6 − 2.6; y = 0, y = 1.0) have been investigated using magnetic measurements, thermal expansion, 57Fe Mössbauer spectroscopy and high resolution neutron powder diffraction methods over the temperature range 10–300 K. The natures of the magnetic transitions in these LaFe13−x−yCoySix compounds have been determined. The Curie temperatures of LaFe13−xSix were found to increase with Si content from TC = 219(5) K for Si content x = 1.6 to TC = 250(5) K for x = 2.6. Substitution of Co for Fe in LaFe10.4Si2.6 resulted in a further …
Magnetic Properties And Magnetocaloric Effect Of Ndmn2-Xcuxsi2 Compounds, M F. Md Din, Jianli Wang, M Avdeev, Q F. Gu, R Zeng, S J. Campbell, S J. Kennedy, S X. Dou
Magnetic Properties And Magnetocaloric Effect Of Ndmn2-Xcuxsi2 Compounds, M F. Md Din, Jianli Wang, M Avdeev, Q F. Gu, R Zeng, S J. Campbell, S J. Kennedy, S X. Dou
Shi Xue Dou
Structural and magnetic properties of NdMn2−x Cu xSi2 compounds (x = 0-1.0) have been investigated by high intensity x-ray and resolution neutron diffraction (3-450 K), specific heat, dc magnetization, and differential scanning calorimetry measurements. Substitution of Cu for Mn leads to an increase in the lattice parameter a but a decrease in c at room temperature. Two magnetic phase transitions have been found for NdMn2−x Cu xSi2 compounds with TN for the antiferromagnetic ordering of Mn-sublatttice and TC for the Nd-sublattice ferromagnetic ordering, respectively. TC increases significantly with increasing Cu content from 36 K at x = 0 to 100 …
Magnetic Properties And Magnetocaloric Effect Of Ndmn2−Xtixsi2 Compounds, M F. Md Din, Jianli Wang, S J. Campbell, R Zeng, W D. Hutchison, M Avdeev, S J. Kennedy, S X. Dou
Magnetic Properties And Magnetocaloric Effect Of Ndmn2−Xtixsi2 Compounds, M F. Md Din, Jianli Wang, S J. Campbell, R Zeng, W D. Hutchison, M Avdeev, S J. Kennedy, S X. Dou
Shi Xue Dou
The structural and magnetic properties of the intermetallic compounds NdMn2−xTixSi2(x = 0, 0.1, 0.2, and 0.3) have been studied by x-ray and high resolution neutron powder diffraction, specific heat, dc magnetization, and differential scanning calorimetry measurements over the temperature range 3–450 K. The Curie temperature and Néel temperature of NdMn2Si2 decrease from TC = 36 K and TN = 380 K to TC = 14 K and TN = 360 K, respectively, on substitution of Ti (x = 0.3) for Mn. The magnetocaloric effect at the first order ferromagnetic phase transition at TC, has been investigated in detail. Under a …
Driving Magnetostructural Transitions In Layered Intermetallic Compounds, Jianli Wang, L Caron, S J. Campbell, S J. Kennedy, M Hofmann, Z X Cheng, M Md Din, A J. Studer, E Bruck, S X. Dou
Driving Magnetostructural Transitions In Layered Intermetallic Compounds, Jianli Wang, L Caron, S J. Campbell, S J. Kennedy, M Hofmann, Z X Cheng, M Md Din, A J. Studer, E Bruck, S X. Dou
Shi Xue Dou
We report the dramatic effect of applied pressure and magnetic field on the layered intermetallic compound Pr0.5Y0.5Mn 2Ge2. In the absence of pressure or magnetic field this compound displays interplanar ferromagnetism at room temperature and undergoes an isostructural first order magnetic transition (FOMT) to an antiferromagnetic state below 158 K, followed by another FOMT at 50 K due to the reemergence of ferromagnetism as praseodymium orders (TCPr). The application of a magnetic field drives these two transitions towards each other, whereas the application of pressure drives them apart. Pressure also produces a giant magnetocaloric effect such that a threefold increase …
Band Structure, Magnetic, And Transport Properties Of Two Dimensional Compounds Sr2-Xgdxcoo4, Q W Yao, Xiaolin Wang, H Kimura, S X. Dou, Konstantin Konstantinov, Z X. Cheng, F Hong, H Zhao, H Qiu, Kiyoshi Ozawa
Band Structure, Magnetic, And Transport Properties Of Two Dimensional Compounds Sr2-Xgdxcoo4, Q W Yao, Xiaolin Wang, H Kimura, S X. Dou, Konstantin Konstantinov, Z X. Cheng, F Hong, H Zhao, H Qiu, Kiyoshi Ozawa
Shi Xue Dou
The layered perovskite compound Sr2-xGdxCoO 4 has not yet been subjected to detailed study so far. In this report, structures, transport, magnetic properties, and first principle calculations will be reported for the two dimensional compounds Sr 2-xGdxCoO4 (x 0.5, 0.75, 1, 1.25). Rietveld refinement revealed that these compounds are crystallized in K2NiF 4-type structures with space group I4/mmm. It was found that the lattice parameter c decreases as x increases. Through the Curies Weiss fitting of the temperature dependent magnetization, it was found that the Sr 1.25Gd0.75CoO4 sample exhibits a weak ferromagnetic to paramagnetic transition at about 62 K, with …
Magnetic Phase Transition And Mossbauer Spectroscopy Of Erni2mnx Compounds, Jianli Wang, S J. Campbell, R Zeng, S. X. Dou, S J. Kennedy
Magnetic Phase Transition And Mossbauer Spectroscopy Of Erni2mnx Compounds, Jianli Wang, S J. Campbell, R Zeng, S. X. Dou, S J. Kennedy
Shi Xue Dou
Investigation of ErNi2Mnx with 0.90 ≤ x ≤ 1.10 indicates that the MgCu2-type structure (with space group Fd-3m) is formed within x = 0.97−1.10. Curie temperature TC = 50 K of ErNi2Mn is significantly higher than those of the corresponding ErNi2 (TC = 7 K) and ErMn2 (TC = 15 K) compounds. Detailed analyses of DC magnetization data demonstrate that the magnetic phase transition at the Curie temperature is second order. The magnetic entropy change around TC has been found to be 4.8 J/kg K for a magnetic field change of 0 to 5 T with its relative cooling power …
Band Structures, Magnetic Properties, And Enhanced Magnetoresistance In The High Pressure Phase Of Gd And Y Doped Two-Dimensional Perovskite Sr2coo4 Compounds, Xiaolin Wang, E Takayama-Muromachi, S X. Dou, Zhenxiang Cheng
Band Structures, Magnetic Properties, And Enhanced Magnetoresistance In The High Pressure Phase Of Gd And Y Doped Two-Dimensional Perovskite Sr2coo4 Compounds, Xiaolin Wang, E Takayama-Muromachi, S X. Dou, Zhenxiang Cheng
Shi Xue Dou
The authors present their studies on the band structures and on the magnetic and magnetotransport properties of the high pressure phase of Sr2-xRExCoO4 [rare earth (RE)=Gd and Y, x=0.1-0.5] compounds which were synthesized by a high pressure and high temperature technique. The authors found that as x increases, the magnetoresistance {(PH-P0)/p0} increases up to -17% at 5 K and 7 T, which is 2.5 times higher than that for undoped Sr2CoO4, although the ferromagnetic transition drops from 255 to 200 K for the Gd doping with x=0.3. The saturation moments at low temperature are significantly enhanced for the Gd doped …
Strong Competition Between The Delta L And Delta T-C Flux Pinning Mechanisms In Mgb2 Doped With Carbon Containing Compounds, Shaban R. Ghorbani, Xiaolin Wang, Md S. Hossain, Qiwen Yao, S X. Dou, Sung-Ik Lee, K C. Chung, Y K. Kim
Strong Competition Between The Delta L And Delta T-C Flux Pinning Mechanisms In Mgb2 Doped With Carbon Containing Compounds, Shaban R. Ghorbani, Xiaolin Wang, Md S. Hossain, Qiwen Yao, S X. Dou, Sung-Ik Lee, K C. Chung, Y K. Kim
Shi Xue Dou
The transport and magnetic properties of 10 wt % malic acid and 5 wt % nanocarbon doped MgB2 have been studied by measuring the resistivity (p), critical current density (jc), connectivity factor (AF), irreversibility field (Hirr), and upper critical field (Hc2). The pinning mechanisms are studied in terms of the collective pinning model. It was found that both mean free path (δl) and critical temperature (δTc) pinning mechanisms coexist in both doped MgB2. For both the malic acid and nanocarbon doped samples, the temperature dependence of the crossover field, which separates the single vortex and the small bundle pinning regime, …
Magnetovolume Effect In Ho2fe17-Xmnx Compounds, Jianli Wang, A J. Studer, S J. Kennedy, R Zeng, S. X. Dou, S J. Campbell
Magnetovolume Effect In Ho2fe17-Xmnx Compounds, Jianli Wang, A J. Studer, S J. Kennedy, R Zeng, S. X. Dou, S J. Campbell
Shi Xue Dou
The structural and magnetic properties of seven compounds in the Ho2Fe17-xMnx series (x = 0-5) have been investigated. The spontaneous magnetization Ms at 10 K exhibits a minimum at x ≈ 3.8 while the 3d-sublattice magnetization MT is found to decrease at ∼ −3.4 μB/per Mn atom compared with the rate of ∼−2.0 μB/per Mn atom expected from a simple dilution model. All of the Ho2Fe17-xMnx compounds exhibit anisotropic thermal expansion below their Curie temperatures leading to the presence of strong magnetovolume effects and Invar-type behavior below TC. An approximately zero volume thermal expansion has been detected between 10 K …