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Title: Combined effects of Sr substitution and pressure on the ground states in CaFe 2 As 2

Here, we present a detailed study of the combined effects of Sr substitution and hydrostatic pressure on the ground-state properties of CaFe 2As 2. Measurements of the electrical resistance and magnetic susceptibility, both at ambient and finite pressure P ≤ 2 GPa, were performed on Ca 1–xSr xFe 2As 2 single crystals grown out of Sn flux. We find that by Sr substitution the transition temperature to the magnetic/structural phase is enhanced and therefore a higher pressure is needed to suppress the transition to lowest temperature. In addition, the transition to the collapsed tetragonal phase is found at a pressure, which is distinctly higher than in the pure compound. This implies that the stability ranges of both phases shift on the pressure-axis upon doping, but the latter one with a higher rate. These observations suggest the possibility of separating the two phase lines, which intersect already at elevated temperatures for x = 0 and low Sr concentration levels. For x = 0.177, we find strong evidence that both phases remain separated down to the lowest temperature and that a zero-resistance state emerges in this intermediate pressure window. This observation indicates that Sr substitution combined with hydrostatic pressure provides another routemore » for stabilizing superconductivity in CaFe 2As 2. Lastly, our results are consistent with the notion that (i) preserving the fluctuations associated with the structural-magnetic transition to low temperatures is vital for superconductivity to form in this material and that (ii) the nonmagnetic collapsed tetragonal phase is detrimental for superconductivity.« less
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  1. J.W. Goethe-Univ. Frankfurt(M), Frankfurt(M) (Germany)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States); Univ. of California, San Diego, CA (United States)
  3. San Diego State Univ., San Diego, CA (United States)
  4. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 14; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1329508