Anton Jesche

A family of binary magnetic icosahedral quasicrystals based on rare earths and cadmium

Examples of stable binary icosahedral quasicrystals are relatively rare, and at present there are no known examples featuring localized magnetic moments. These would represent an ideal model system for attaining a deeper understanding of the nature of magnetic interactions in aperiodic lattices. Here we report the discovery of a family of at least seven rare earth icosahedral binary quasicrystals, i-R-Cd (Ru2009 = u2009Gdxa0toxa0Tm, Y), six of which bear localized magnetic moments. Our work highlights the importance of carefully motivated searches through phase space and supports the proposal that, like icosahedral Sc12Zn88 (ref.xa0), binary quasicrystalline phases may well exist nearby known crystalline approximants, perhaps as peritectically forming compounds with very limited liquidus surfaces, offering very limited ranges of composition/temperature for primary solidification.

Single crystal growth from light, volatile and reactive materials using lithium and calcium flux

We present a method for the solution growth of single crystals from reactive Li and Ca melts and its application to the synthesis of several, representative compounds. Among these, single crystalline LiN, Li(Li)N with = {Mn, Fe, Co}, LiCaN, LiC, LiRh and LiIr from Li-rich flux, as well as CaN, CaNi, CaNi, YbNi, YNi and LaNi from Ca-rich flux could be obtained. Special emphasize is given on the growth of nitrides using commercially available LiN and CaN powders as the nitrogen source instead of N gas.

Alternating magnetic anisotropy of Li2(Li1–xTx)N (T = Mn, Fe, Co, and Ni)

Substantial amounts of the transition metals Mn, Fe, Co, and Ni can be substituted for Li in single crystalline Li2(Li1–xTx)N. Isothermal and temperature-dependent magnetization measurements reveal local magnetic moments with magnitudes significantly exceeding the spin-only value. The additional contributions stem from unquenched orbital moments that lead to rare-earth-like behavior of the magnetic properties. Accordingly, extremely large magnetic anisotropies have been found. Most notably, the magnetic anisotropy alternates as easy plane→easy axis→easy plane→easy axis when progressing from T = Mn → Fe → Co → Ni. This behavior can be understood based on a perturbation approach in an analytical, single-ion model. As a result, the calculated magnetic anisotropies show surprisingly good agreement with the experiment and capture the basic features observed for the different transition metals.

Fermi surface reconstruction in (Ba1−xKx)Fe2As2 (0.44 x 1) probed by thermoelectric power measurements

We report in-plane thermoelectric power measurements on single crystals of (Ba1−xKx)Fe2As2 (0.44 x 1). We observe a minimum in the S|T =const versus x at x ∼ 0.55 that can be associated with the change in the topology of the Fermi surface, a Lifshitz transition, related to the electron pockets at the center of M point crossing the Fermi level. This feature is clearly observable below ∼75 K. Thermoelectric power also shows a change in the x ∼ 0.8–0.9 range, where the maximum in the thermoelectric power collapses into a plateau. This Lifshitz transition is most likely related to the reconstruction of the Fermi surface associated with the transformation of the hole pockets at the M point into four blades as observed by ARPES measurements.

Antiferroelectric instability in the kagome francisites Cu3Bi(SeO3)2O2X ( X=Cl,Br )

Density-functional calculations of lattice dynamics and high-resolution synchrotron powder diffraction uncover antiferroelectric distortion in the kagome francisite Cu

Single Crystal Growth and Anisotropic Magnetic Properties of Li2Sr[Li1 − xFexN]2

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Magnetic and transport properties of i-R-Cd icosahedral quasicrystals (R=Y,Gd-Tm)

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Nearly itinerant ferromagnetism in CaNi2 and CaNi3

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Extreme Field Sensitivity of Magnetic Tunneling in Fe-Doped Li3N

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Interplay betweenCo3dandCe4fmagnetism in CeCoAsO

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