Martin Meven

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Y. Su,1,* P. Link,2 A. Schneidewind,3 Th. Wolf,4 P. Adelmann,4 Y. Xiao,5 M. Meven,2 R. Mittal,1,6 M. Rotter,7 D. Johrendt,7 Th. Brueckel,1,5 and M. Loewenhaupt3 1Juelich Centre for Neutron Science, IFF, Forschungszentrum Juelich, Outstation at FRM II, Lichtenbergstrasse 1, D-85747 Garching, Germany 2FRM II, Technische Universitaet Muenchen,(More)
Introduction Sample description and mineralogy Experimental methods: 1) Chemical analyses 2) Single-crystal neutron diffraction experiment 3) Mössbauer spectroscopy Results: Neutron structure refinement of axinite Results: Mössbauer spectrum of axinite Discussion Concluding remarks Acknowledgements References Table and Figure captions Corresponding author:(More)
N,N-Dimethylbiguanidinium bis(hydrogensquarate) features an impressive range of hydrogen bonds within the same crystal structure: neighbouring anions aggregate to a dianionic pair through two strong O-H···O interactions; one of these can be classified among the shortest hydrogen bonds ever studied. Cations and anions in this organic salt further interact(More)
In the antiferromagnetic ground state, below TN ≃ 5.7 K, Ca2CoSi2O7 exhibits strong magnetoelectric coupling. For a symmetry-consistent theoretical description of this multiferroic phase, precise knowledge of its crystal structure is a prerequisite. Here we report the results of single-crystal neutron diffraction on Ca2CoSi2O7 at temperatures between 10 and(More)
We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on the choice of the mold, typical rods(More)
Synthetic Co(2)SiO(4) crystallizes in the olivine structure (space group Pnma) with two crystallographically non-equivalent Co positions and shows antiferromagnetic ordering below 50 K. We have investigated the temperature variation of the Co(2)SiO(4) magnetic structure by means of non-polarized and polarized neutron diffraction for single crystals.(More)
We report vibrating coil magnetometry of the spin-ice system Ho(2)Ti(2)O(7) down to ~0.04 K for magnetic fields up to 5 T applied parallel to the [111] axis. History-dependent behavior emerges below T(0)(*) ~ 0.6 K near zero magnetic field, in common with other spin-ice compounds. In large magnetic fields, we observe a magnetization plateau followed by a(More)
Single-crystal neutron diffraction was used to investigate the H-atom disorder in triammonium hydrogen disulfate (TAHS), (NH4)3H(SO4)2, below room temperature. Crystal structure analysis of the monoclinic phase III shows an increase of proton ordering with decreasing temperature in the (SO4)H(SO4) dimer. Moreover, the NH4(+) groups on a general position(More)
The highly disordered crystal structure of triammonium hydrogen disulfate, (NH(4))(3)H(SO(4))(2), in the high-temperature phase I was studied using single-crystal neutron diffraction. It is known that the O atom involved in hydrogen bonding between neighbouring SO(4) tetrahedra is disordered and takes a split-atom position, building a two-dimensional(More)
Strontium titanate (SrTiO 3) is one of the best studied substances showing a displacive phase transition [1]. At ambient temperature, it exhibits a cubic perovskite structure with the space group Pm3m. On cooling, a Brillouin zone-boundary softmode drives the second-order transition to an antiferrodis-tortive phase at T C = 105 K. The primary order(More)