Local order in Cr-Fe-Co-Ni: Experiment and electronic structure calculations
Sax, C. R.
Peil, O. E.
Ruban, A. V.
Permanent link to this recordhttp://hdl.handle.net/10754/631137
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AbstractA quenched-in state of thermal equilibrium (at 723 K) in a single crystal of Cr-Fe-Co-Ni close to equal atomic percent was studied. Atom probe tomography revealed a single-phase state with no signs of long-range order. The presence of short-range order (SRO) was established by diffuse x-ray scattering exploiting the variation in scattering contrast close to the absorption edges of the constituents: At the incoming photon energies of 5969, 7092, and 8313 eV, SRO maxima that result from the linear superposition of the six partial SRO scattering patterns, were always found at X position. Electronic structure calculations showed that this type of maximum stems from the strong Cr-Ni and Cr-Co pair correlations, that are furthermore connected with the largest scattering contrast at 5969 eV. The calculated effective pair interaction parameters revealed an order-disorder transition at approximately 500 K to a L12-type (Fe,Co,Ni)3Cr structure. The calculated magnetic exchange interactions were dominantly of the antiferromagnetic type between Cr and any other alloy component and ferromagnetic between Fe, Co, and Ni. They yielded a Curie temperature (TC) of 120 K, close to experimental findings. Despite the low value of TC, the global magnetic state strongly affects chemical and elastic interactions in this system. In particular, it significantly increases the ordering tendency in the ferromagnetic state compared to the paramagnetic one.
CitationSchönfeld B, Sax CR, Zemp J, Engelke M, Boesecke P, et al. (2019) Local order in Cr-Fe-Co-Ni: Experiment and electronic structure calculations. Physical Review B 99. Available: http://dx.doi.org/10.1103/PhysRevB.99.014206.
SponsorsThe authors are grateful to E. Fischer for growing the single crystal. They gratefully acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation at beamline ID01. B.S. thanks KAUST for providing measuring time for the APT studies. A.V.R. acknowledges the support of the Swedish Research Council (VR project 2015-05538), a European Research Council grant, the VINNEX center Hero-m, financed by the Swedish Governmental Agency for Innovation Systems (VINNOVA), Swedish industry, and the Royal Institute of Technology (KTH). Calculations were done using NSC (Linköping) and PDC (Stockholm) resources provided by the Swedish National Infrastructure for Computing (SNIC). A.V.R. and O.E.P. also acknowledge the financial support under the scope of the COMET program within the K2 Center “Integrated Computational Material, Process and Product Engineering (IC-MPPE)” (Project No 859480). This program is supported by the Austrian Federal Ministries for Transport, Innovation and Technology (BMVIT) and for Digital and Economic Affairs (BMDW), represented by the Austrian research funding association (FFG), and the federal states of Styria, Upper Austria and Tyrol.
PublisherAmerican Physical Society (APS)
JournalPhysical Review B