Cascade of field-induced magnetic transitions in a frustrated antiferromagnetic metal

Frustrated magnets can exhibit many novel forms of order when exposed to high magnetic fields, however, much less is known about materials where frustration occurs in the presence of itinerant electrons. Here we report thermodynamic and transport measurements on micron-sized single crystals of the triangular-lattice metallic antiferromagnet 2H-AgNiO2, in magnetic fields of up to 90 T and temperatures down to 0.35 K. We observe a cascade of magnetic phase transitions at 13.5 20, 28 and 39T in fields applied along the easy axis, and we combine magnetic torque, specific heat and transport data to construct the field-temperature phase diagram. The results are discussed in the context of a frustrated easy-axis Heisenberg model for the localized moments where intermediate applied magnetic fields are predicted to stabilize a magnetic supersolid phase. Deviations in the measured phase diagram from this model predictions are attributed to the role played by the itinerant electrons.

受挫磁体在强磁场中会呈现出许多新奇的有序形式，然而，对于存在巡游电子时发生受挫的材料，人们所知甚少。在此，我们报道了对三角晶格金属反铁磁体2H - AgNiO₂的微米级单晶在高达90特斯拉的磁场以及低至0.35开尔文的温度下进行的热力学和输运测量。我们观察到在沿易轴施加磁场时，在13.5、20、28和39特斯拉处出现一系列磁相变，并且我们结合磁转矩、比热和输运数据构建了磁场 - 温度相图。我们在局域磁矩的受挫易轴海森堡模型的背景下对结果进行了讨论，该模型预测中间施加的磁场会稳定一个磁超固态相。测量得到的相图与该模型预测的偏差归因于巡游电子所起的作用。