Abstract
Within the BaFe2As2 crystal lattice, we partially substitute thallium for barium and report the effects of interlayer coupling in Ba1-xTlxFe2As2 crystals. We demonstrate the unusual effects of magneto-elastic coupling and charge doping in this iron-arsenide material, whereby Néel temperature rises with small x, and then falls with additional x. Specifically, we find that Néel and structural transitions in BaFe2As2 (TN = Ts = 133 K) increase for x = 0.05 (TN = 138 K, Ts = 140 K) from magnetization, heat capacity, resistivity, and neutron diffraction measurements. Evidence from single crystal X-ray diffraction and first principles calculations attributes the stronger magnetism in x = 0.05 to magneto-elastic coupling related to the shorter intraplanar Fe-Fe bond distance. With further thallium substitution, the transition temperatures decrease for x = 0.09 (TN = Ts = 131 K), and this is due to charge doping. We illustrate that small changes related to 3d transition-metal state can have profound effects on magnetism.
Original language | English |
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Article number | 21660 |
Journal | Scientific Reports |
Volume | 6 |
DOIs | |
State | Published - Feb 12 2016 |
Funding
This work was primarily supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Science and Engineering Division (A.S., M.M., B.S.), and Chemical Sciences, Geosciences, and Biosciences Division (R.C.). This study was partially funded (L.L., D.P.) by ORNL’s Lab-Directed Research & Development (LDRD). The work at ORNL’s High Flux Isotope Reactor (HFIR) was sponsored by the Scientific User Facilities Division, Office of BES, U.S. DOE (H.C.). We appreciate S. Kuhn’s assistance in chemical composition (EDS) measurements.