Evidence for Coexistence of Bulk Superconductivity and Itinerant Antiferromagnetism in the Heavy Fermion System CeCo(In1−xCdx)5

Abstract

In the generic phase diagram of heavy fermion systems, tuning an external parameter such as hydrostatic or chemical pressure modifies the superconducting transition temperature. The superconducting phase forms a dome in the temperature—tuning parameter phase diagram, which is associated with a maximum of the superconducting pairing interaction. Proximity to antiferromagnetism suggests a relation between the disappearance of antiferromagnetic order and superconductivity. We combine muon spin rotation, neutron scattering, and x-ray absorption spectroscopy techniques to gain access to the magnetic and electronic structure of CeCo(In1−xCdx)5 at different time scales. Different magnetic structures are obtained that indicate a magnetic order of itinerant character, coexisting with bulk superconductivity. The suppression of the antiferromagnetic order appears to be driven by a modification of the bandwidth/carrier concentration, implying that the electronic structure and consequently the interplay of superconductivity and magnetism is strongly affected by hydrostatic and chemical pressure.

Solubility of Nanocrystalline Cerium Dioxide: Experimental Data and Thermodynamic Modeling

“…Previous works have shown that Ce-M 4,5 -edge XANES spectra provide distinct signatures for the Ce 3+ and Ce 4+ oxidation states, although the ability to fully deconvolve mixtures of oxidation states is limited to about 5% for bulk materials 56,[65][66][67] . Spectra for the CeO 2 NPs closely resemble published O K-edge [68][69][70] and Ce M 5,4 -edge 56,[66][67][68][71][72][73] spectra for CeO 2 obtained using a variety of detection methods, which confirms that subsequent solution-phase studies were conducted on analytes that were pure and homogenous. Some very small shape distortions of the spectrum can be attributed to either the presence of the surface hydroxyl groups, or Ce(III) at the NP interface.…”

Magnetic structure of Cd-doped CeIrIn$_5$

“…The commensurate magnetic order with Q AF = (1/2, 1/2, 1/2) determined here for CeIr(In 0.9 Cd 0.1 ) 5 is also strikingly different from that in pure CeRhIn 5 , in which an incommensurate magnetic structure with Q AF = (1/2, 1/2, 0.297) was reported 24,[32][33][34] . On the other hand, the same commensurate magnetic ordering wave vector was observed in Cd-doped CeCoIn 5 [18][19][20] , in which superconductivity coexists with magnetic order over a wide range of Cd concentrations (Fig. 1(a)).…”

“…To determine the Néel temperature, the data were fitted by a phenomenological function I/I 0 = 1 − (T /T N ) α , with α a free parameter. This function was successfully used to fit the temperature dependence of the magnetic Bragg peak intensity in other heavy fermion compounds, such as CePd 2 Si 2 25,26 , Sn-doped CeRhIn 5 12 , Cd-doped CeRhIn 5 18 , and CePt 2 In 7 27 . The best fit is obtained with α = 2.0 ± 0.5 and T N = 3.0 ± 0.1 K. The latter value is consistent with T N determined from previous specific heat 17 and resistivity 22 measurements.…”

“…The magnetic structure of Cd-doped CeCoIn 5 was previously investigated by elastic neutron scattering for nominal Cd concentrations of 6% (T N ≈ T c ≈ 2 K) 18 , 7.5% (T N ≈ 2.4 K, T c ≈ 1.7 K) 19 , and 10% (T N ≈ 3 K, T c ≈ 1.3 K) 20 . In all studies, magnetic intensity was observed only at the ordering wave vector Q AF = (1/2, 1/2, 1/2) commensurate with the crystal lattice.…”

“…Here x is the nominal Cd content of crystals. Arrows indicate Cd concentrations, for which the magnetic structure was determined by neutron diffraction in previous studies for CeCo(In1−xCdx)5[18][19][20] and in this work for CeIr(In1−xCdx)5.…”