Geometric and Magnetic Structures of K₂ReI₆ as an Antiferromagnetic Insulator with Ferromagnetic Spin-Canting Originated from Spin–Orbit Coupling

Journal Article · 03 January 2019 · Journal of Physical Chemistry. C

DOI: https://doi.org/10.1021/acs.jpcc.8b11371 · OSTI ID:1558475

Gui, Xin ^[1]; Calder, Stuart A.  ^[2]; Cao, Huibo  ^[2]; Yu, Tianyi ^[1]; Xie, Weiwei  ^[1]

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1. Louisiana State Univ., Baton Rouge, LA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

We present the results of a crystallographic analysis, magnetic characterization including neutron powder diffraction, and theoretical assessment of K₂ReI₆ prepared using solvent reactions. K₂ReI₆ crystallizes in the space group P2₁/n with an inversion center. Magnetic measurements of K₂ReI₆ sample indicate dominant antiferromagnetic coupling with a Curie–Weiss temperature of θ_W = –63.3(1) K, effective magnetic moment ~2.64 μ_B/Re but show a weak ferromagnetism ordered at ~24 K. Neutron powder diffraction indicates long-range order of the Re spins below 24 K, with an ordered magnetic moment of 2.2(1) μ_B/Re at 1.5 K. Therefore, a canted antiferromagnetic structure is concluded. The electronic structures using first-principles calculations suggest that the antiferromagnetic model of K₂ReI₆ yields the lowest total energy and opens a band gap with ~1.0 eV width, which is consistent with the UV–vis–NIR optical measurements. After including the spin–orbit coupling (SOC) into the calculation, the band degeneracies slightly shift without influencing the band gap. Furthermore, the results imply that K₂ReI₆ is an antiferromagnetic insulator with weak ferromagnetic spin-canting resulting from strong SOC-entangled ground state S = 3/2.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1558475
• Journal Information: Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 3 Vol. 123; ISSN 1932-7447
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY