Segregation of antiferromagnetism and high-temperature superconductivity in Ca1-xLaxFe2As2 Academic Article uri icon

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abstract

  • We report the effect of applied pressures on magnetic and superconducting order in single crystals of the aliovalent La-doped iron pnictide material Ca$_{1-x}$La$_{x}$Fe$_{2}$As$_{2}$. Using electrical transport, elastic neutron scattering and resonant tunnel diode oscillator measurements on samples under both quasi-hydrostatic and hydrostatic pressure conditions, we report a series of phase diagrams spanning the range of substitution concentrations for both antiferromagnetic and superconducting ground states that include pressure-tuning through the antiferromagnetic (AFM) quantum critical point. Our results indicate that the observed superconducting phase with maximum transition temperature of $T_{c}$=47 K is intrinsic to these materials, appearing only upon suppression of magnetic order by pressure tuning through the AFM critical point. In contrast to all other intermetallic iron-pnictide superconductors with the ThCr$_2$Si$_2$ structure, this superconducting phase appears to exist only exclusively from the antiferromagnetic phase in a manner similar to the oxygen- and fluorine-based iron-pnictide superconductors with the highest transition temperatures reported to date. The unusual dichotomy between lower-$T_{c}$ systems with coexistent superconductivity and magnetism and the tendency for the highest-$T_{c}$ systems to show non-coexistence provides an important insight into the distinct transition temperature limits in different members of the iron-based superconductor family.

authors

  • Saha, Shanta R
  • Drye, T
  • Goh, SK
  • Klintberg, LE
  • Silver, JM
  • Grosche, FM
  • Sutherland, M
  • Munsie, TJS
  • Luke, Graeme
  • Pratt, DK
  • Lynn, JW
  • Paglione, J

publication date

  • April 23, 2014