Coexistence of commensurate and incommensurate antiferromagnetic ground states in Co_𝑥⁢NbSe₂ single crystal

Journal Article · Tue Jan 21 00:00:00 EST 2025 · Physical Review Materials

DOI:https://doi.org/10.1103/PhysRevMaterials.9.014403· OSTI ID:2586839

Mandujano, H. Cein ^[1]; Zavalij, Peter Y. ^[1]; Manjón-Sanz, Alicia ^[2]; Cao, Huibo ^[2]; Rodriguez, Efrain E. ^[1]

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1. Univ. of Maryland, College Park, MD (United States)
2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

In Co_𝑥⁢NbSe₂, crystal symmetry and cobalt site occupation drive the formation of two distinct magnetic phases. At 𝑥=1/4, the centrosymmetric structure (𝑃⁢6₃/𝑚⁢𝑚⁢𝑐) promotes Co-Co interactions leading to the formation of an 𝐴-type antiferromagnetic structure phase with a transition temperature of 𝑇$$^𝐴_𝑁$$=169K. At 𝑥=1/3, the noncentrosymmetric structure (𝑃⁢6₃⁢22) induces a lower-temperature magnetic phase with 𝑇$$^S_𝑁$$=28K. We report the coexistence of both substructures within a superlattice, with a nuclear propagation vector of (1/3, 1/3, 0) relative to the host lattice. Single crystals of Co_0.28⁢NbSe₂ exhibit both magnetic transitions, with 𝑇$$^𝐴_𝑁$$ corresponding to the 𝑥∼1/4 phase and 𝑇$$^S_𝑁$$ corresponding to the 𝑥∼1/3 phase. Magnetic susceptibility and specific heat measurements confirm these transitions, although only the high-temperature 𝑇$$^𝐴_𝑁$$ phase significantly affects resistivity. We successfully isolate each phase in powder samples, while single crystals with an intercalation ratio of 𝑥=0.28 display the coexistence of both phases in a single sample. Using single-crystal neutron diffraction, we solved the magnetic structure of the high-temperature centrosymmetric phase (𝑇$$^𝐴_𝑁$$), and neutron powder diffraction revealed the double-𝑞 magnetic structure of the low-temperature noncentrosymmetric phase (𝑇$$^S_𝑁$$).

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-06CH11357; AC05-00OR22725; SC0016434
• OSTI ID: 2586839
• Journal Information: Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 1 Vol. 9; ISSN 2475-9953
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

RKKY interaction
magnetic phase transitions
spin density waves