Ultrahigh magnetic field study on Gd2BaNiO5: Suppression of the Haldane gap

Physical Review B (США). 2024. Vol. 110. No. 21. Article 214439.

Bykov A., Temnikov F., Korshunov A., Kozabaranov R., Kudasov Y., Makarov I., Maslov D., Platonov V., Repin P., Strelkov I., Surdin O., Selemir V., Bychkova E., Bochkarev A., Katenkov P., Filippov A., Moskin A., Попова Е. А., Irkhin V., Streltsov S., Vasiliev A.

Ultrahigh magnetic field up to 300 T obtained by explosive flux compression has been applied to study the interplay of two qualitatively different magnetic subsystems in Gd2BaNiO5, i.e., the S = 1 nickel chain system with the spin-singlet gapped ground state and S = 7/2 gadolinium system forming a distorted triangular lattice, which orders at TN = 55 K. The measurements show that the magnetization of the Gd subsystem rapidly saturates at ∼14μB/f.u. This is followed by the further increase of magnetization at the critical field HC1 = 90 ± 20 T, where the Haldane gap starts to close. Theoretical classical and quantum Monte Carlo calculations demonstrate that HC1 is strongly affected by the staggered field of Gd spins, which effectively increases the Haldane gap by a frustrating exchange interaction, and show that the full magnetization saturation of both Gd and Ni subsystems is expected at the critical field HC2 ∼ 800 T.

Ключевые слова: сильные магнитные поля, электронная структура, Electronic structure, First-principles calculations, High magnetic fields, Magnetic interactions, Расчеты на основе первых принципов, магнитные взаимодействия

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