title: 57Fe Mössbauer studies across the spin density wave transition in BaFe2-xRuxAs2.
abstract: Mössbauer measurements have been carried out in powdered single crystalline samples of BaFe(2-x)RuxAs(2), for Ru concentration in the x = 0.0-0.5 range. The internal hyperfine field (B(hf)) measured at 5 K is found to decrease with an increase in Ru concentration, consistent with the disappearance of a magnetic ground state with Ru substitution. The temperature dependent Mössbauer measurements have been used to study the evolution of magnetic ordering at the Fe sites, in samples with a Ru fraction of x = 0.1 and 0.5. From the analysis of the data, it is surmised that the isomer shift increases with a decrease in temperature, with a characteristic slope change at the structural transition in both samples studied. In both the x = 0.1 and x = 0.5 samples, a low B(hf) centred around 0.5 Tesla is seen to occur well above the structural transition temperature, the contribution from which is suppressed with a decrease in temperature. Below the structural transition temperature, a bimodal distribution of B(hf) centred at about 3 Tesla and 5 Tesla emerges, the contribution from which increases with a further decrease in temperature. Spin polarized density functional calculations suggest the occurrence of different magnetic moments at the Fe sites in the Ru substituted compounds, and provide a rationale for the experimentally observed multimodel B(hf).
authors.affiliation: UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India.
authors.forename: V
authors.initials: V
authors.lastname: Raghavendra Reddy
authors.forename: A
authors.initials: A
authors.lastname: Bharathi
authors.forename: Ajay
authors.initials: A
authors.lastname: Gupta
authors.forename: Kavita
authors.initials: K
authors.lastname: Sharma
authors.forename: Sharat
authors.initials: S
authors.lastname: Chandra
authors.forename: Shilpam
authors.initials: S
authors.lastname: Sharma
authors.forename: K
authors.initials: K
authors.lastname: Vinod
authors.forename: C S
authors.initials: CS
authors.lastname: Sundar