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Structural Collapse and Superconductivity in Rare-Earth-Doped CaFe2As2



S. R. Saha, N. P. Butch, T. Drye, J. Magill, S. Ziemak, K. Kirshenbaum, P. Y. Zavalij, Jeffrey W. Lynn, J. Paglione


The interplay between structural, magnetic and superconducting properties in the newly discovered iron-based superconducting compounds has been a central theme in attempts to elucidate the nature of Cooper pairing in this new family of high-temperature superconductors [1, 2]. In particular, manipulation of the electronic structure via chemical substitution or applied pressure is thought to play a key role in both the disruption of antiferromagnetic order and the stabilization of superconductivity with transition temperatures as high as 55 K in oxygen and fluorine-based iron-pnictide materials [3¿6]. Here we present the stunning observation of 45 K superconductivity in electron-doped CaFe2As2, presenting the highest Tc in the intermetallic class of iron-based superconductors. The use of aliovalent rare earth substitution into the alkaline earth site allows us to tune both the lattice density and charge doping in this system, resulting in a controllably induced structural collapse of the tetragonal unit cell by choice of substituent ion size. Remarkably, the superconductivity appears to persist independent of the presence of a structural collapse, despite an abrupt change in electronic structure at the onset of interlayer bonding. These results convey important implications for the role of the anionic tetrahedral framework and its interlayer coupling in attaining high-Tc superconductivity in iron-based materials.
Physical Review B


Iron Superconductivity, Magnetic Order, Structural Phase Transition, Neutron Diffraction


Saha, S. , Butch, N. , Drye, T. , Magill, J. , Ziemak, S. , Kirshenbaum, K. , Zavalij, P. , Lynn, J. and Paglione, J. (2012), Structural Collapse and Superconductivity in Rare-Earth-Doped CaFe<sub>2</sub>As<sub>2</sub>, Physical Review B, [online], (Accessed June 14, 2024)


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Created January 12, 2012, Updated October 12, 2021