| Autor: |
Zhang S; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States., Yang X; Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States., Wooten BL; Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, United States., Bag R; Department of Physics, Duke University, Durham, North Carolina 27708, United States., Yadav L; Department of Physics, Duke University, Durham, North Carolina 27708, United States., Moore CE; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States., Parida S; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States., Trivedi N; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States., Lu Y; Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States., Heremans JP; Department of Mechanical & Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, United States., Haravifard S; Department of Physics, Duke University, Durham, North Carolina 27708, United States., Wu Y; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States. |
| Abstrakt: |
The realization and discovery of quantum spin liquid (QSL) candidate materials are crucial for exploring exotic quantum phenomena and applications associated with QSLs. Most existing metal-organic two-dimensional (2D) quantum spin liquid candidates have structures with spins arranged on the triangular or kagome lattices, whereas honeycomb-structured metal-organic compounds with QSL characteristics are rare. Here, we report the use of 2,5-dihydroxy-1,4-benzoquinone (X 2 dhbq, X = Cl, Br, H) as the linkers to construct cobalt(II) honeycomb lattices (NEt 4 ) 2 [Co 2 (X 2 dhbq) 3 ] as promising Kitaev-type QSL candidate materials. The high-spin d 7 Co 2+ has pseudospin-1/2 ground-state doublets, and benzoquinone-based linkers not only provide two separate superexchange pathways that create bond-dependent frustrated interactions but also allow for chemical tunability to mediate magnetic coupling. Our magnetization data show antiferromagnetic interactions between neighboring metal centers with Weiss constants from -5.1 to -8.5 K depending on the X functional group in X 2 dhbq linkers (X = Cl, Br, H). No magnetic transition or spin freezing could be observed down to 2 K. Low-temperature susceptibility (down to 0.3 K) and specific heat (down to 0.055 K) of (NEt 4 ) 2 [Co 2 (H 2 dhbq) 3 ] were further analyzed. Heat capacity measurements confirmed no long-range order down to 0.055 K, evidenced by the broad peak instead of the λ-like anomaly. Our results indicate that these 2D cobalt benzoquinone frameworks are promising Kitaev QSL candidates with chemical tunability through ligands that can vary the magnetic coupling and frustration. |
