Coincident structural and magnetic order inBaFe2(As1−xPx)2revealed by high-resolution ne

Abstract

We present neutron diffraction analysis of BaFe2(As1−xPx)2 over a wide temperature (10 to 300 K) and compositional (0.11 ≤ x ≤ 0.79) range, including the normal state, the magnetically ordered state, and the superconducting state. The paramagnetic to spin-density wave and orthorhombic to tetragonal transitions are first order and coincident within the sensitivity of our measurements (∼ 0.5 K). Extrapolation of the orthorhombic order parameter down to zero suggests that structural quantum criticality cannot exist at compositions higher than x = 0.28, which is much lower than values determined using other methods, but in good agreement with our observations of the actual phase stability range. The onset of spin-density wave order shows a stronger structural anomaly than the charge-doped system in the form of an enhancement of the c/a ratio below the transition.

Ultrafast Structural Dynamics of the Fe-Pnictide Parent CompoundBaFe2As2

“…However, the atomic displacement at the fluence of F ≈ 0.5 mJ/cm 2 based on band structure calculations [3] yields a maximal increase of the magnetic moment of 0.08µ B , which corresponds to a relative change of ∼ 11% [33]. This leads to an increase of T N by ∼ 20 K, if we consider the ratio of the SDW transition temperature and the Fe magnetic moments of 200 − 250 K/µ B observed in Ba 1−x K x Fe 2 As 2 [33] and BaFe 2 (As 1−x P x ) 2 [34]. Given the fact that the transient magnetic ordering has also been observed > 100 K above T N [15], the increased magnetic moments cannot be solely responsible for the resurrection of SDW order, but the transiently modified nesting properties of the band structure need to be also considered [15].…”

Detailed magnetic and structural analysis mapping a robust magneticC4dome inSr1−xNaxFe2Taddei1, Allred2, Bugaris3 et al. 2016Phys. Rev. BSelf Cite419501View full textAdd to dashboardCite

“…Discriminating between these two models is complicated by the fact that magnetoelastic coupling ensures that the onset of one order parameter triggers the other, 9 and indeed the structural and magnetic phase transitions are coincident and first-order in many of the iron pnictides. [10][11][12][13] However, a resolution of this issue will provide strong constraints on the origin and symmetry of the superconducting order parameter.…”

Coupling of structure to magnetic and superconducting orders in quasi-one-dimensional K2Cr3As3

“…For temperatures T > 40 K a linear thermal expansion is observed (with nearly negligable change for T < 40 K) with no evidence of a structural response which might arise from nuclear or magnetic orderings in contrast to DFT calculations' predictions but in accord with featureless tansport data 6,7,11 . While it is possible that the relatively large steps in temperature between 300 K and 20 K might miss a subtle lattice response, such as that commonly reported for the FBS, comparisons of the high temperature and low temperature patterns do not reveal the presence of new peaks, peak splitting or other evidence of a phase transition (see SM) [24][25][26] . Such structural stability, despite a predicted Peierls instability, has also been observed in the Q1D chevrel family (Tl 2 Mo 6 Se 6 ) which share the DWS structural motif [27][28][29] .…”