A key role for unusual spin dynamics in ferropnictides

By I. Mazin, Michael Johannes. 2008

150 citations recorded by the source corpus.

The discovery of high-Tc ferropnictides introduced a new family of superconductors, and has already revealed a complicated and often contradictory picture of the structural and magnetic properties. An almost unprecedented sensitivity of the calculated magnetism and Fermi surface to structural details prevents correspondence to experiment. Experimental probes of the order parameter are in surprisingly strong disagreement, even considering the relative immaturity of the field. We outline various and seemingly contradictory evidence, both theoretical and experimental, and show it can be rectified by assuming a large-moment spin density wave, well defined but with magnetic twin and antiphase boundaries, dynamic on the experimental timescale. Under this assumption, calculations can accurately reproduce even very fine details of the structure, and a natural explanation for the temperature separation of structural and magnetic transitions is provided. Thus, our theory restores agreement between experiment and theory in crucial areas, making further cooperative progress possible on both fronts. Many studies on the properties of the recently discovered ferropnictide superconductors report seemingly contradictory results. A theoretical study suggests that these contradictions might be resolved by considering such materials as having a strongly magnetic ground state whose domain boundaries fluctuate, preventing their experimental detection.

Subfields: Accounting, Condensed Matter Physics, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/2bc2ee21a2eaa12eefd0b9996644c9b7603aa803

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Citations in the corpus

Superconductivity in iron compounds (2011, background): “However, a number of early theories (Yildirim, 2008; Mazin and Johannes, 2009) suggested that the lower transition temperature magnetism causes the structural transition through a fluctuating magnetic state without long range order (see Singh, 2009 for a discussion).”
Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides. (2011, background): “It has been advocated that the shortcomings of DFT can be circumvented by incorporating the physics of long wavelength fluctuations [5].”
In-plane electronic anisotropy of underdoped ‘122’ Fe-arsenide superconductors revealed by measurements of detwinned single crystals (2011, background): “Chu J-H, Analytis J G, Kucharczyk C and Fisher I R (2009), Determination of the phase diagram of the electron-doped superconductor Ba(Fe1−xCox)2As2 , Phys.”