磁场诱导的选区自旋间隙闭合与量子临界性在BaNd$_2$ZnS$_5$中
Field-Induced Selective Spin Gap Closure and Quantum Criticality in BaNd$_2$ZnS$_5$
AI总结：
研究发现BaNd$_2$ZnS$_5$中磁场诱导选区自旋间隙闭合，展现模式选择性量子临界性，揭示强各向异性相互作用导致不同激发子集独立临界。
摘要：
我们报告了BaNd$_2$ZnS$_5$ (BNZS) 中磁场诱导的模式选择性量子临界性的热力学证据。在Neel温度TN = 2.9 K以下，自旋轨道纠缠的Nd$^3+$自旋在磁场作用下形成两种对称性不等价的低能自旋激发模式，源于Kramers双态物理，具有不同的间隙Delta_L和Delta_H。对于沿[110]方向施加的磁场，较低能隙Delta_L连续软化并在临界场Hc ~ 2 T处消失，而较高能隙Delta_H保持为间隙，使系统处于部分临界相。尽管临界性部分存在，热力学测量揭示了连续的量子相变。交流磁化率显示普适的标度行为，chi_ac(T, H) 能够塌缩到单一标度函数，并在临界点遵循chi_ac ~ T^-0.2。有限的残余Sommerfeld系数gamma_0进一步表明在量子临界点附近出现局限于单个对称性子集的无隙激发。与基于全局低能激发软化的传统量子临界性不同，BNZS由于其强各向异性相互作用表现出Kramers双态激发的选择性破坏。我们的结果确立了BNZS作为一种自旋轨道耦合的稀土磁体，其中量子临界性不是全局的，而是模式选择性的，各向异性相互作用使不同激发子集独立表现出临界性。
英文摘要：
We report thermodynamic evidence for field-induced mode-selective quantum criticality in the layered rare-earth magnet BaNd2ZnS5 (BNZS). Below the Neel temperature TN = 2.9 K, spin-orbit-entangled Nd3+ moments form two symmetry-inequivalent low-energy spin-excitation modes arising from Kramers doublet physics under a magnetic field, with distinct gaps Delta_L and Delta_H. For magnetic fields applied along the [110] direction, the lower-energy gap Delta_L softens continuously and collapses at a critical field Hc ~ 2 T, while the higher-energy gap Delta_H remains gapped, leaving the system in an intermediate partially critical phase. Despite the partial nature of the criticality, thermodynamic measurements reveal a continuous quantum phase transition. The ac susceptibility shows universal scaling behavior, with chi_ac(T, H) collapsing onto a single scaling function and following chi_ac ~ T^-0.2 at criticality. A finite residual Sommerfeld coefficient gamma_0 further indicates the emergence of gapless excitations confined to a single symmetry sector near the quantum critical point. In contrast to conventional quantum criticality based on global softening of low-energy excitations, BNZS exhibits a selective breakdown of Kramers-doublet excitations due to its strong anisotropic interactions. Our results establish BNZS as a spin-orbit-coupled rare-earth magnet where quantum criticality is not global but mode-selective, with anisotropic interactions enabling independent criticality in distinct excitation sectors.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
