Effect of pressure cycling on Iron: Signatures of an electronic instability and unconventional superconductivity

Abstract

High pressure electrical resistivity and x-ray diffraction experiments have been performed on Fe single crystals. The crystallographic investigation provides direct evidence that in the martensitic $bcc\to hcp$ transition at 14 GPa the $\{110{\}}_{bcc}$ become the $\{002{\}}_{hcp}$ directions. During a pressure cycle, resistivity shows a broad hysteresis of 6.5 GPa, whereas superconductivity, observed between 13 and 31 GPa, remains unaffected. Upon increasing pressure an electronic instability, probably a quantum critical point, is observed at around 19 GPa and, close to this pressure, the superconducting $T_c$ and the isothermal resistivity ($0<T<300$K) attain maximum values. In the superconducting pressure domain, the exponent $n=5/3$ of the temperature power law of resistivity and its prefactor, which mimics $T_c$, indicate that ferromagnetic fluctuations may provide the glue for the Cooper pairs, yielding unconventional superconductivity.

References in corpus (4)

• Signatures of valence fluctuations in CeCu2Si2 under high pressure
• Spin-fluctuation dominated electrical transport of Ni3Al at high pressure
• Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition
• Mechanism for the α -> ε phase transition in iron

Cited by in corpus (6)

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• Electronic correlations in dense iron: from moderate pressure to Earth's core conditions
• Magnetic fluctuations and superconducting pairing in $\epsilon$-iron