Complex evolution of the magnetic transitions and unexpected absence of bulk superconductivity in chemically precompressed NaMn6Bi5

Abstract

Pressurized AMn6Bi5 (A=K,Rb,Cs) members have recently emerged as a new family of ternary manganese-based superconductors that exhibits a broad superconducting dome with a maximum critical temperature up to ∼9.5K adjacent to the long-range antiferromagnetic phase in their T−P phase diagrams. The analogous compound NaMn6Bi5, with a smaller A-site cation and lower antiferromagnetic transition temperatures T1≈46K and T2≈52K is expected to show superconductivity at lower pressures. By performing detailed high-pressure electrical transport measurements on the chemically precompressed NaMn6Bi5 single crystals, we map out the complex evolution with pressure of its multiple magnetic transitions, which are eventually suppressed by pressures. Contrary to the expectation, the bulk superconductivity is absent near the magnetic quantum critical point, where we observed a weak decrease in resistance below 2.4 K in a narrow pressure range of 12 to 14.4 GPa from the measurements in a diamond anvil cell. The origin of this anomaly remains unclear, and it might be ascribed to the presence of filamentary superconductivity in analogy to other AMn6Bi5. These distinct results of NaMn6Bi5 with respect to other AMn6Bi5 members highlight the complexity of magnetism and its interplay with superconductivity in this family of quasi–one-dimensional compounds.

Source-reported materials — not catalogue approval

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