Fast recovery of the pristine magnetic and structural phases in superconducting LaFeAsO_0.89F_0.11 by Mn/Fe substitution

Abstract

We report on an experimental study of the effect of Mn impurities in the optimally doped LaFe-AsO0.89F0.11 compound. The results show that a very tiny amount of Mn, of the order of 0.1%, is enough to destroy superconductivity and to recover at low temperatures both the magnetic ground state and the orthorhombic structure of the pristine LaFeAsO parent compound. The results are discussed within a model where electron correlations enhance the Ruderman-Kittel-Kasuya-Yosida interaction among impurities.

Mn-induced Fermi-surface reconstruction in the SmFeAsO parent compound

“…Below , the onset of a commensurate orthorhombic SDW order in SmFeAsO (either or ) breaks the rotational symmetry. Thus, without loss of generality, we set and consider only a finite , with the magnetization direction along the x -direction, as established experimentally 3 , 4 . It is worth noting that here the spin-orbit coupling ( ) plays an important role, since it fixes the value of the magnetic moment to be parallel to the ordering wavevector.…”

The huge effect of Mn substitution on the structural and magnetic properties of LaFeAsO: the La(Fe,Mn)AsO system

“…Among all the different types of chemical substitution examined in LnFeAsO compounds, the optimally electrondoped La(Fe 1−x Mn x )As(O 0.89 F 0.11 ) system stands out for its peculiar behaviour. In fact, an anomalously huge and unexplained suppression of superconductivity by Mn-substitution as small as x ~ 0.2% characterizes this system, whereas static magnetism is recovered for x ~ 0.1% [15,16] (notably, the recovery of magnetism is coupled with the reestablishment of the orthorhombic structure [17]). This behaviour recalls the anomalous suppression of superconductivity accompanied by a recovery of magnetism observed in the (La 2−x Ba x )CuO 4 system for a hole concentration corresponding to x ~ 1/8; remarkably, in this and other similar systems a static charge density wave appears, which is associated with the suppression of superconductivity and stems from the pinning of dynamical charge density waves [18][19][20].…”

Structural strain and competition between charge density wave and superconductivity in La(Fe,Mn)As(O0.89FMartinelli1, Carretta2, Moroni3 et al. 2021Phys. Rev. BSelf Cite3120View full textAdd to dashboardCite

“…Among all, Mn substitution at the Fe site stands out, since it triggers unusual changes in these materials; in principle, Mn substitution should act as hole doping, but it is actually detrimental to superconductivity. In fact, optimally electron-doped La(Fe 1-x Mn x )As(O 0.89 F 0.11 ) samples exhibit an anomalously huge suppression of superconductivity by Mn substitution as small as x ∼ 0.002, whereas static short-range magnetism is recovered for x 0.001 [13,14]. In Nd-and Sm-based systems, superconduc-* alberto.martinelli@spin.cnr.it tivity is also suppressed, but the amount of Mn substitution is more than 10 times larger [15,16].…”