Pressure-induced Superconductivity in UIr

Tuning of superconductivity by Ni substitution into noncentrosymmetric ThCo1−xNixC2

“…9,10 Research interest into NCS superconductors expanded significantly after the discovery of unconventional superconductivity in CePt3Si, 11 along with other heavy fermion (HF) compounds such as UIr, CeRhSi3 and CeIrSi3. [12][13][14] However, the coexistence with magnetism and strong electron-correlation in the HF compounds greatly complicates the underlying physics due solely to the NCS crystal structure, as both effects can give rise to unconventional superconductivity. It is therefore highly desirable to explore the superconductivity in weakly correlated NCS systems in order to study the effect of the ASOC on the superconducting state.…”

Non-Fermi Liquid Regimes and Superconductivity in the Low Temperature Phase Diagrams of Strongly Correlated d- and f-Electron Materials

“…Yet a third magnetic transition appears above ∼1.4 GPa at ∼30 K and is monotonically suppressed continuously to zero temperature near P c3 ∼ 2.7 GPa. Superconductivity with a maximum temperature T c ∼ 0.14 K appears in a very narrow dome localized around P C3 [208]. The superconductivity has been observed by zero electrical resistance and by a drop in the ac magnetic susceptibility [226,228]; however, thermodynamic signatures of the superconducting transition (via, e.g., ac calorimetry) have not, to our knowledge, been reported.…”

“…Within the temperature interval between T c and T C , the ferromagnetism and superconductivity coexist macroscopically (in a spatially inhomogeneous manner), whereas a new sinusoidallymodulated state with a wavelength ∼100 Å and superconductivity coexist microscopically (within the same volume element) [206]. In contrast, the recently discovered uranium-based compounds UGe 2 (under pressure) [207], URhGe [24], UIr (under pressure) [208,209], and UCoGe [210] appear to exhibit the microscopic coexistence of superconductivity and true itinerant electron ferromagnetism. Such a coexistence is intriguing since, in a conventional superconductor, the large internal field generated by the ferromagnetic order would be expected to destroy the superconducting state by breaking the spin-singlet Cooper pairs [211].…”

“…The superconducting critical temperature T c has been multiplied by a factor of 50. (b), (c), and (d) show the parameters given by fitting the low temperature electrical resistivity of single crystalline samples with ρ(T ) = ρ 0 + AT n [208]. (e) Pressure dependence of the ordered magnetic moment for two different samples, as determined by either residual magnetization or Arrott plot analysis [226] indicates the itinerant nature of the ferromagnetism.…”

“…The presence of superconductivity in a ferromagnetic material which lacks inversion symmetry raises some interesting questions about the symmetry of the superconducting order parameter [229]. Figure 21(e) displays the pressure dependence of the ordered moments for the various ferromagnetic phases as a function of pressure, as determined by residual magnetization or Arrott plot analysis [208,226]. Within the FM1 phase, the ordered moment decreases monotonically with pressure and just below P C1 has dropped to roughly half of the ambient pressure value.…”