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Title: Spin order and dynamics in the diamond-lattice Heisenberg antiferromagnets CuRh 2 O 4 and CoRh 2 O 4

Here, antiferromagnetic insulators on a diamond lattice are candidate materials to host exotic magnetic phenomena ranging from spin-orbital entanglement to degenerate spiral ground states and topological paramagnetism. Compared to other three-dimensional networks of magnetic ions, such as the geometrically frustrated pyrochlore lattice, the investigation of diamond-lattice magnetism in real materials is less mature. In this work, we characterize the magnetic properties of model A-site spinels CoRh 2O 4 (cobalt rhodite) and CuRh 2O 4 (copper rhodite) by means of thermomagnetic and neutron-scattering measurements, and we perform group theory analysis, Rietveld refinement, mean-field theory, and spin-wave theory calculations to analyze the experimental results. Our investigation reveals that cubic CoRh 2O 4 is a canonical S = 3/2 diamond-lattice Heisenberg antiferromagnet with a nearest-neighbor exchange J = 0.63 meV and a Néel ordered ground state below a temperature of 25 K. In tetragonally distorted CuRh 2O 4, competing exchange interactions between up to third-nearest-neighbor spins lead to the development of an incommensurate spin helix at 24 K with a magnetic propagation vector k m = (0,0,0.79). Strong reduction of the ordered moment is observed for the S = 1/2 spins in CuRh 2O 4 and captured by our 1/ S corrections tomore » the staggered magnetization. Our work identifies CoRh 2O 4 and CuRh 2O 4 as reference materials to guide future work searching for exotic quantum behavior in diamond-lattice antiferromagnets.« less
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  1. Georgia Inst. of Technology, Atlanta, GA (United States)
  2. Oregon State Univ., Corvallis, OR (United States)
  3. Georgia Inst. of Technology, Atlanta, GA (United States); Univ. of Cambridge, Cambridge (United Kingdom)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Univ. of California, Santa Cruz, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 6; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1374655