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189 results on '"Akselrud L"'

2. Refinement of the crystal structure of Bi-II, at 2.54 GPa

Author

Akselrud L. G., Hanfland M., and Schwarz U.

Subjects
Physics, QC1-999, Crystallography, QD901-999
Abstract

Bi, monoclinic, C12/m1 (No. 12), a = 6.67256(1) Å, b = 6.1108(2) Å, c = 3.30013(9) Å, β = 110.412(2)°, V = 126.1 Å3, Z = 4, R(P) = 0.118, R(I) = 0.087, T = 295 K, P = 2.54 GPa.

Published
2003
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5. Single crystal growth of CeTAl$_3$ (T = Cu, Ag, Au, Pd and Pt)

Author

Franz, C., Senyshyn, A., Regnat, A., Duvinage, C., Schönmann, R., Bauer, A., Prots, Y., Akselrud, L., Hlukhyy, V., Baran, V., and Pfleiderer, C.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Abstract

We report single crystal growth of the series of CeTAl$_3$ compounds with T = Cu, Ag, Au, Pd and Pt by means of optical float zoning. High crystalline quality was confirmed in a thorough characterization process. With the exception of CeAgAl$_3$, all compounds crystallize in the non-centrosymmetric tetragonal BaNiSn$_{3}$ structure (space group: I4mm, No. 107), whereas CeAgAl$_3$ adopts the related orthorhombic PbSbO$_2$Cl structure (Cmcm, No. 63). An attempt to grow CeNiAl$_3$ resulted in the composition CeNi$_2$Al$_5$. Low temperature resistivity measurements down to $\sim$0.1K did not reveal evidence suggestive of magnetic order in CePtAl$_3$ and CePdAl$_3$. In contrast, CeAuAl$_3$, CeCuAl$_3$ and CeAgAl$_3$ display signatures of magnetic transitions at 1.3K, 2.1K and 3.2K, respectively. This is consistent with previous reports of antiferromagnetic order in CeAuAl$_3$, and CeCuAl$_3$ as well as ferromagnetism in CeAgAl$_3$, respectively., Comment: 12 pages, 6 figures

Published
2016
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8. Structural investigations on $\epsilon$-FeGe at high pressure and low temperature

Author

Wilhelm, H., Schmidt, M., Cardoso-Gil, R., Burkhardt, U., Hanfland, M., Schwarz, U., and Akselrud, L.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

The structural parameters of $\epsilon$-FeGe have been determined at ambient conditions using single crystal refinement. Powder diffraction have been carried out to determine structural properties and compressibility for pressures up to 30 GPa and temperatures as low as 82 K. The discontinuous change in the pressure dependence of the shortest Fe-Ge interatomic distance might be interpreted as a symmetry-conserving transition and seems to be related to a magnetic phase boundary line., Comment: 4 pages, 5 figures

Published
2007
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9. Metallic State in Cubic FeGe beyond its Quantum Phase Transition

Author

Pedrazzini, P., Wilhelm, H., Jaccard, D., Jarlborg, T., Schmidt, M., Hanfland, M., Akselrud, L., Yuan, H. Q., Schwarz, U., Grin, Yu., and Steglich, F.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

We report on results of electrical resistivity and structural investigations on the cubic modification of FeGe under high pressure. The long-wavelength helical order ($T_C=280$ K) is suppressed at a critical pressure $p_c\approx 19$ GPa. An anomaly in the resistivity data at $T_X(p)$ and strong deviations from a Fermi-liquid behavior in a wide pressure range above $p_c$ suggest that the suppression of $T_C$ disagrees with the standard notion of a quantum critical phase transition. The metallic ground state persisting at high pressure can be described by band-structure calculations if structural disorder due to zero-point motion is included. Discontinuous changes in the pressure dependence of the shortest Fe-Ge interatomic distance occurring close to the $T_C(p)$ phase line could be interpreted as a symmetry-conserving transition of first order., Comment: 4 pages, 4 figures

Published
2006
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12. Valence fluctuations in the 3D+3 modulated Yb3Co4Ge13 Remeika Phase

Author

Feig, M., Akselrud, L., Motylenko, M., Bobnar, M., Wagler, J., Kvashnina, K. O., Rafaja, D., Leithe-Jasper, A., and Gumeniuk, R.

Abstract

Yb3Co4Ge13 is the first example of a Remeika phase with a 3D + 3 [space group P43n(a,0,0)000(0,a,0)000(0,0,a)000; a = 8:72328(1) Å, Q1 = Q2 = Q3 = 0:4974(2)] modulated crystal structure. A slight shift of the composition towards higher Ybcontent (i:e: Yb3:2Co4Ge12:8) leads to the disappearance of the satellite reflections and stabilization of the disordered primitive cubic [space group Pm3n, a = 8:74072(2) Å] Remeika prototype structure. The stoichiometric structurally modulated germanide is a metal with hole-like charge carriers, where Yb-ions are in a temperature dependent intermediate valence state of +2:60+2:66 for the temperature range 85-293 K. The valence fluctuations have been investigated by means of temperature dependent X-ray absorption spectroscopy, magnetic susceptibility and thermopower measurements

Published
2021

19. Polar structure formation in solid solution of strontium substituted fluorapatite-gelatin composites: from structural and morphogenetic aspects to pyroelectric properties

Author

Knaus, J., Sommer, M., Duchstein, P., Gumeniuk, R., Akselrud, L. G., Sturm, S., Auffermann, G.-D., Hennig, C., Zahn, D., Hulliger, J., and Sturm, E. V.

Subjects
apatite,strontiumsubstitution,composite,morphogenesis,crystalstructure,polarity
Abstract

Strontium substituted apatite-(CaF)-gelatin composites have been synthesized within a gelatin gel using the dou-ble diffusion technique. All experimental parameters were kept constant while systematically varying the strontium/ calcium molar ratio in solution. The effect of the presence of strontium ions in the growth solution on composition, morphogenesis and morphology as well as pyroelectric properties of synthetic aggregates was systemically analyzed. It was shown that stron-tium ions significantly inhibit the growth process of composite aggregates and increase growth anisotropy along [0001], which were also confirmed and explained by molecular dynamic simulations. Furthermore, it was observed the promotion of the crystal branching processes and spherulite formation. Pyroelectric microscopy (SPEM) measurements on mixed substi-tuted apatite-(CaSrF)-gelatin composite aggregates showed an increase in polar properties, suggesting a lowering of the crys-tal symmetry. This was verified by Rietveld refinement of synchrotron pXRD, which revealed the non-centrosymmetric P63apatite crystal structure. These data could shed new light on understanding piezoelectric and pyroelectric properties of apa-tite based biological hard tissues.

Published
2020

29. Single crystal growth of CeTAl3 (T = Cu, Ag, Au, Pd and Pt)

Author

Franz, C., primary, Senyshyn, A., additional, Regnat, A., additional, Duvinage, C., additional, Schönmann, R., additional, Bauer, A., additional, Prots, Y., additional, Akselrud, L., additional, Hlukhyy, V., additional, Baran, V., additional, and Pfleiderer, C., additional

Published
2016
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30. Discovery and Characterization of Antiferromagnetic UFe5As3

Author

Zaremba, N., Krnel, M., Prots, Yu., König, M., Akselrud, L., Grin, Yu., and Svanidze, E.

Abstract

This work presents a study on a new uranium iron arsenide UFe5As3. By implementing Bi-flux synthesis, we were able to grow mm-sized single crystals of this compound, which show twinning. UFe5As3is one of only two known uranium iron arsenides. It adopts a monoclinic, UCr5P3-type crystal structure (space group P21/m, Pearson symbol mP18, a= 7.050(2) Å, b= 3.8582(9) Å, c= 9.634(1) Å, β = 100.25(1)°). The magnetic susceptibility of UFe5As3indicates it to be an antiferromagnet with TN= 47 K and μeff= 4.94 μBper formula unit, signaling that both U and Fe are likely magnetic in this material. The material appears to be anisotropic, with a small (likely ferromagnetic) spin reorientation transition around T= 29 K. The Sommerfeld coefficient γ0= 135 mJ mol–1K–2suggests enhanced effective electron mass in UFe5As3, while electrical resistivity indicates metallic, Kondo-like behavior.

Published
2024
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33. The 5:7 Member of the Spin-Ladder Series in the Bi-Sr-Ca-Cu-O System

Author

Zaremba, O., Shcherban, O., Akselrud, L., Roman Gladyshevskii, Banfi, F., and Giannini, E.

Subjects
strongly correlated, General Physics and Astronomy, cristallography, Settore FIS/03 - FISICA DELLA MATERIA, nanoscale materials, Settore FIS/01 - FISICA SPERIMENTALE
Published
2010

34. The 5:7 Member of the Spin-Ladder Series in the Bi-Sr-Ca-Cu-O System

Author

Zaremba, O, Shcherban, O, Akselrud, L, Gladyshevskii, R, Banfi, Francesco, Giannini, E., Banfi, Francesco (ORCID:0000-0002-7465-8417), Zaremba, O, Shcherban, O, Akselrud, L, Gladyshevskii, R, Banfi, Francesco, Giannini, E., and Banfi, Francesco (ORCID:0000-0002-7465-8417)

Abstract

The crystal structure of the (Bi(0.02)Sr(0.39)Ca(0.59))(10)Cu(17)O(29) spin ladder compound was determined from single-crystal X-ray diffraction data. The precursor powder was prepared from stoichiometric amounts of SrCO(3), CaCO(3), CuO, and Bi(2)O(3) by calcination at 820 degrees C for 20 h and pressed to form a rod used for the crystal growth. The travelling-solvent-floating-zone method was applied in an image furnace to grow large single crystals. The composite commensurate structure was solved and refined in space group F222, Pearson symbol oF224, a = 11.340(2), b = 12.829(2), c = 19.441(3) angstrom, Z = 4. The composite incommensurate structure of the (Bi(0.02)Sr(0.39)Ca(0.59) (10)Cu(17)O(29) compound was solved and refined in the (3 + 1)-space group F222(00 gamma), a = 11.340(2), b = 12.829(2), c(1) = 2.7773(4), c(2) = 3.8882(6) angstrom, q = 0.7143.

Published
2010

36. Disorder in the composite crystal structure of the manganese `disilicide' MnSi1.73 from powder X-ray diffraction data.

Author

Akselrud, L., Cardoso Gil, R., Wagner-Reetz, M., and Grin, Yu.

Subjects
*X-ray diffraction, *SILICON compounds, *TRANSITION metals, *CRYSTALLOGRAPHY
Abstract

The crystal structure of the higher manganese silicide MnSi1.7 (known in the literature as HMS) is investigated in samples with different compositions obtained by different techniques at temperatures not higher than 1273 K. Powder X-ray diffraction was applied. The crystal structure is described as incommensurate composite. In addition to the ordered model already known in the literature, the partial disorder in the silicon substructure was detected and described introducing an additional atomic site with a different modulation function. [ABSTRACT FROM AUTHOR]

Published
2015
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