572 research outputs found
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 Li3N, Li2(Li{1-x}Tx)N with T = {Mn,
Fe, Co}, LiCaN, Li2C2, LiRh, and LiIr from Li-rich flux as well as Ca2N, CaNi2,
CaNi3, YbNi2, Y2Ni7, and LaNi5 from Ca-rich flux could be obtained. Special
emphasize is given on the growth of nitrides using commercially available Li3N
and Ca3N2 powders as the nitrogen source instead of N2 gas.Comment: 40 pages, 20 figures, reference list update
Preserved entropy and fragile magnetism
A large swath of strongly correlated electron systems can be associated with
the phenomena of preserved entropy and fragile magnetism. In this overview we
present our thoughts and plans for the discovery and development of lanthanide
and transition metal based, strongly correlated systems that are revealed by
suppressed, fragile magnetism or grow out of preserved entropy. We will present
and discuss current examples such as YbBiPt, YbAgGe, YbFe2Zn20, PrAg2In,
BaFe2As2, CaFe2As2, LaCrSb3 and LaCrGe3 as part of our motivation and to
provide illustrative examples
Magnetic ordering in GdNi2B2C revisited by resonant x-ray scattering: evidence for the double-q model
Recent theoretical efforts aimed at understanding the nature of
antiferromagnetic ordering in GdNi2B2C predicted double-q ordering. Here we
employ resonant elastic x-ray scattering to test this theory against the
formerly proposed, single-q ordering scenario. Our study reveals a satellite
reflection associated with a mixed-order component propagation wave vector,
viz., (q_a,2q_b,0) with q_b = q_a approx= 0.55 reciprocal lattice units, the
presence of which is incompatible with single-q ordering but is expected from
the double-q model. A (3q_a,0,0) wave vector (i.e., third-order) satellite is
also observed, again in line with the double-q model. The temperature
dependencies of these along with that of a first-order satellite are compared
with calculations based on the double-q model and reasonable qualitative
agreement is found. By examining the azimuthal dependence of first-order
satellite scattering, we show the magnetic order to be, as predicted,
elliptically polarized at base temperature and find the temperature dependence
of the "out of a-b plane" moment component to be in fairly good agreement with
calculation. Our results provide qualitative support for the double-q model and
thus in turn corroborate the explanation for the "magnetoelastic paradox"
offered by this model.Comment: 8 pages, 5 figures. Submitted to Phys. Rev.
Specific heat jump at the superconducting transition temperature in Ba(Fe(1-x)Cox)2As2 and Ba(Fe(1-x)Nix)2As2 single crystals
We present detailed heat capacity measurements for Ba(Fe(1-x)Cox)2As2 and
Ba(Fe(1-x)Nix)2As2 single crystals in the vicinity of the superconducting
transitions. The specific heat jump at the superconducting transition
temperature (Tc), Delta Cp/Tc, changes by a factor ~ 10 across these series.
The Delta Cp/T$ vs. Tc data of this work (together with the literature data for
Ba(Fe0.939Co0.061)2As2, (Ba0.55K0.45)Fe2As2, and (Ba0.6K0.4)Fe2As2) scale well
to a single log-log plot over two orders of magnitude in Delta Cp/Tc and over
about an order of magnitude in Tc, giving Delta Cp/Tc ~ Tc^2
- …