504 research outputs found
Was the Ediacaran Shuram Excursion a globally synchronized early diagenetic event? Insights from methane-derived authigenic carbonates in the uppermost Doushantuo Formation, South China
The Ediacaran Period is characterized by the most profound negative carbon isotope (
β-Nd2Mo4O15
The title compound, dineodymium(III) tetraÂmolybdate(VI), has been prepared by a flux technique and is the second polymorph of composition Nd2Mo4O15. The crystal structure is isotypic with those of Ce2Mo4O15 and Pr2Mo4O15. It features a three-dimensional network composed of distorted edge- and corner-sharing NdO7 polyhedra, NdO8 polyhedra, MoO4 tetraÂhedra and MoO6 octaÂhedra
Phase evolution of Ce-based heavy-fermion superconductors under pressure: a combined DFT+DMFT and effective-model description
In typical Ce-based heavy-fermion superconductors, superconducting (SC)
phases emerge or can be tuned in proximity to the antiferromagnetic (AF)
quantum critical point (QCP), but so far the explicit phase-evolution process
and the coexistence of superconductivity and AF order near the QCP remain lack
of understanding. Here, by combing DFT+DMFT with effective-model calculations,
we provide a theoretical description for Ce-based SC compounds under pressure.
Firstly, DFT+DMFT calculations for the normal states reveal that the Kondo
hybridizations are significantly enhanced, while the initially localized
electrons eventually become fully itinerant via a localized-itinerant
crossover. In this context, we construct an effective model with tunable
parameters under pressure, and show that the interplay of magnetic correlation
and Kondo hybridization can drive successive transitions, from AF phase to
AF+SC coexisting phase, then to paramagnetic SC phase via an AF transition
which corresponds to the QCP, and finally to Kondo paramagnetic phase through a
SC transition driven by localized-itinerant crossover. Our study gives a proper
explanation for the pressure-induced magnetic QCP and SC transition, and for
the phase-evolution process under pressure in typical Ce-based superconductors,
and may also help to understand the SC states emerging around the ferromagnetic
quantum transition points in uranium-based superconductors.Comment: 13 pages, 11 figure
- …