Resolution of the discrepancy between the variation of the physical properties of Ce_1-xYb_xCoIn₅single crystals and thin films with Yb composition

Abstract

The extraordinary electronic phenomena found in the Ce 1--x Yb x CoIn 5 system have attracted much interest. These phenomena include an Yb valence transition, a change in Fermi surface topology, and suppression of the heavy fermion quantum critical field at a nominal concentration x ≈ 0.2, which, surprisingly, have no discernable effect on the unconventional superconductivity and normal--state non--Fermi liquid behavior that occur over a broad range of x up to ~0.8. However, the variation of the coherence temperature T* and the superconducting critical temperature T c with nominal Yb

Universal heat conduction inCe1−xYbxCoIn5: Evidence for robust nodald-wave superconducting gap

“…This suggests that our determination of the actual Yb concentrations for our single crystals is accurate, and further confirms the conclusion of Ref. [18]. According to Ref.…”

“…Recently, the anomalous phenomena observed in Ce 1−x Yb x CoIn 5 system have attracted much attention [16][17][18][19][20][21][22][23][24][25][26]. At first, the violation of Vegard's law was found in Ce 1−x Yb x CoIn 5 single crystals, together with the robustness of T c and Kondocoherence temperature T coh upon Yb doping [16].…”

“…However, later measurements on the Ce 1−x Yb x CoIn 5 thin films demonstrated a verification of Vegard's law, and strong suppression of T c and T coh with Yb doping [17]. To solve this discrepancy, Jang et al carefully determined the actual Yb concentration x act in Ce 1−x Yb x CoIn 5 single crystals, and found that x act is only about 1/3 of the nominal value x nom up to x nom ≈ 0.5 [18]. With x act , the rate of T c suppression with Yb concentration for the single crystals is nearly the same as that observed in the thin films [18].…”

Pressure studies of the quantum critical alloyCe0.93Yb0.07CoIn5

“…These crystals have a nominal Yb doping x nom = 0.2 and an actual doping x act = 0.07. The crystal structure and unit cell volume were determined from X-ray powder diffraction measurements, while the actual composition was determined according to the method developed by Jang et al 24 Since all previous publications on this system give the nominal Yb concentration instead of the actual concentration, in this paper we use the nominal concentrations whenever referring to the results of earlier publications in order to be consistent with their reports, while we use the actual Yb concentration when we refer to the present work. We note that the study by Jang et al 24 has shown that x act ≈ 1 3 x nom , providing that the nominal Yb doping is less than about 40 %.…”

A theoretical evaluation of magnetoresitance (magneto transport property) of some heavy-fermion superconductors

“…The presence of the linear term in MR is a sign of broken inversion symmetry of the system. There is some recent calculations [40][41][42][43][44][45] which also reveals similar behaviour. …”