Incommensurate spin density wave versus local magnetic inhomogeneities in Ba(Fe_1−xNi_x)₂As₂: a⁵⁷Fe Mössbauer spectral study

Abstract

We report 57 Fe Mössbauer spectral results in pure and doped Ba(Fe 1−x Ni x ) 2 As 2 with x = 0.01 and 0.03. We show that all these materials present a first-order magnetic transition towards a magnetically ordered state. In the doped compounds, a broad distribution of Fe hyperfine fields is present in the magnetic phase. We successfully fit the Mössbauer data in Ba(Fe 1−x Ni x ) 2 As 2 in the framework of two different models: (i) an incommensurate spin density wave (IC-SDW); (ii) a dopant-induced perturbation of the Fe polarization, recently proposed to interpret 75 As NMR data in Ba(Fe 1−x Ni x ) 2 As 2 , which is valid only in the very dilute limit x = 0.01. Moreover, we show here that these NMR data can also be successfully analysed in terms of the 'incommensurate model' for all doping contents by using the parameters obtained from the Mössbauer spectral analysis. Therefore it is not possible to rule out the presence of an IC-SDW on the basis of the 75 As NMR data.

Superconductivity and antiferromagnetism in Ba0.75K0.25Fe2AsMunévar1, Micklitz2, Agüero3 et al. 2013Phys. Rev. B12550View full textAdd to dashboardCite

“…15 However, as we have shown in another paper on 57 Fe Mössbauer spectroscopy in BaFe 2−x Ni x As 2 pnictides, a "two-site model" can satisfactorily fit all spectra below T N . 4 In this "two-site model" a magnetic and a nonmagnetic site are used.…”

Structural and magnetic properties of transition metal substituted BaFe₂As₂ compounds studied by x-ray and neutron scattering

“…To compare the effect of Ru substitution (isoelectronic-doping) and Mn substitution (hole- Either C-AFM order or IC-AFM order are predicted by detailed band structure calculations, [305,306] and several local probe measurements such as 75 As nuclear spin resonance [184], 57 Fe Mössbauer [307,308], and muon spin resonance measurements [309] showed that it is probable that it is indeed an IC-AFM structure in Ba(Fe 1−x T M x ) 2 (T M = Co and Ni) compounds.…”

“…NMR measurements [184,308,310] by some groups on underdoped Ba(Fe 1−x Co x ) 2 As 2 (x = 0.02, 0.04) [310] and (x = 0.06) [184] found a strong broadening of the 75 As lines attributable to the appearance of a distribution of internal fields at low temperatures in the magnetically ordered state. A strong anisotropy was also observed, with the broadening more pronounced for H c than for H a b.…”

Crystal structure and magnetic modulation in β−Ce2O2FeSe2

“…The Ce 3+ contribution makes estimation of T N (Fe) from the magnetic data difficult, though we observe a sharp maximum around 80 K in dχT /dT and a broader maximum around 145 K. The overall behavior is consistent with that of the (diamagnetic) La analog β-La 2 O 2 FeSe 2 , which shows non-Curie-Weiss behavior with a broad hump in susceptibility around 91 K which coincides with the loss of magnetic neutron scattering at the Nèel temperature T N . [26], BiFeO 3 [27,28], and AgFeO 2 [29]), iron arsenide superconductors (e.g., doped BaFe 2 As 2 [30,31]), and systems such as Fe x V 3−x S 4 [32], FeP [33], CuFeSe 2 , and CuFeTe 2 [34]. Values of the isomer shift δ and quadrupole splitting E Q , derived by fitting to the paramagnetic spectra (T > 90 K), are presented in Fig.…”