NaCuMoO₄(OH) as a Candidate Frustrated J₁-J₂ Chain Quantum Magnet

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In a frustrated J₁-J₂ chain with the nearest-neighbor ferromagnetic interaction J₁ and the next-nearest-neighbor antiferromagnetic interaction J₂, novel magnetic states such as a spin-nematic state are theoretically expected. However, they have been rarely examined in experiments because of the difficulty in obtaining suitable model compounds. We show here that the quasi-one-dimensional antiferromagnet NaCuMoO₄(OH), which comprises edge-sharing CuO₂ chains, is a good candidate J₁-J₂ chain antiferromagnet. The exchange interactions are estimated as J₁ = - 51 K and J₂ = 36 K by comparing the magnetic susceptibility, heat capacity, and magnetization data with the data obtained using calculations by the exact diagonalization method. High-field magnetization measurements at 1.3 K show a saturation above 26 T with little evidence of a spin nematic state expected just below the saturation field, which is probably due to smearing effects caused by thermal fluctuations and the polycrystalline nature of the sample.