基泰耶夫量子自旋液体候选材料BaCo2(AsO4)2中的场致一级相变和相共存
Field-induced first order transitions and phase coexistence in the Kitaev quantum spin liquid candidate BaCo2(AsO4)2
浏览论文内容
中文总结 AI 辅助
研究BaCo2(AsO4)2在磁场中的相变，利用中子散射等方法，发现其场致双锯齿到UUD转变有局域自旋激发簇，UUD到FM相变是一级相变且有相共存，结果不支持临界场附近量子自旋液体情形，模型解释了相关现象。
中文摘要 AI 辅助
BaCo2(AsO4)2（BCAO）是具有丰富低温相图的绝缘基泰耶夫量子自旋液体候选材料。低于5K时，它呈现双锯齿磁序。施加面内磁场时，磁结构先在0.12T附近转变为上-上-下（UUD）态，然后在0.5T附近进入完全自旋极化铁磁（FM）态。在接近极化相的窄场区域，有有限的残余热导率报道，暗示可能存在场致量子自旋液体相。利用中子散射表明，0.15T附近场致双锯齿到UUD转变伴随着与传统自旋波共存的局域UUD自旋激发簇的出现。进一步增加磁场，BCAO经历UUD到FM的一级相变，UUD和FM相共存，伴随自旋塞贝克系数的急剧响应。这些结果不支持UUD到FM临界场附近的量子自旋液体情形。相反，模型表明宽激发源于束缚自旋翻转对，并解释了自旋塞贝克响应的符号及临界场附近的热导率。
英文摘要
BaCo2(AsO4)2 (BCAO) is an insulating Kitaev quantum spin liquid candidate with a rich low-temperature phase diagram. Below 5 K, it exhibits double-zigzag magnetic order. Upon application of an in-plane magnetic field, the magnetic structure first transforms into an up-up-down (UUD) state near 0.12 T and then enters a fully spin-polarized ferromagnetic (FM) state near 0.5 T. In the narrow field regime close to the polarized phase, a finite residual thermal conductivity has been reported, suggesting a possible field-induced quantum spin liquid phase. Using neutron scattering, we show that the field-induced double-zigzag-to-UUD transition near 0.15 T is accompanied by the emergence of a cluster of localized UUD spin excitations that coexist with conventional spin waves. Upon further increasing field, BCAO undergoes a first-order UUD-to-FM transition with coexistence of UUD and FM phases, accompanied by a sharp response in the spin Seebeck coefficient. These results do not support a quantum spin liquid scenario near the UUD-to-FM critical field. Instead, modeling indicates that the broad excitations arise from bound spin-flip pairs, while a low-lying dispersive branch near the FM phase boundary carries the same sign of magnetization as the FM order. These excitations naturally account for the observed sign of the spin Seebeck response and are likely relevant to the thermal conductivity near the critical field.
