二维磁转变两侧的不同临界指数
Different critical exponents on two sides of the magnetic transition in two dimensions
- Institute of Physics, Bhubaneswar（印度巴布奈斯瓦尔物理研究所）
- Homi Bhabha National Institute, Anushaktinagar, Mumbai（孟买阿努沙克提纳加尔霍米·巴巴国立研究所）
- Institute of Chemical Technology–IndianOil Odisha Campus, Bhubaneswar（巴布奈斯瓦尔印度石油奥里萨校区化学技术研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过临界标度分析，在准二维杂化钙钛矿(C7H9NBr)2CuBr4中实验实现了磁转变温度上下分别呈现2D Ising型和2D XY型非对称临界指数，揭示了Dzyaloshinskii-Moriya相互作用的关键作用。
AI中文摘要：
磁转变两侧可能存在不同临界指数这一可能性已在三维系统中被理论预测[PRB 13, 2222 (1976), PRL 115, 200601 (2015)]并实验实现[PRL 128, 015703 (2022)]。然而，这种情形在二维系统中的出现尚未被证实。在此，我们通过对准二维非中心对称、具有Dzyaloshinskii-Moriya相互作用（DMI）活性的杂化钙钛矿(C7H9NBr)2CuBr4进行临界标度分析，报道了在磁转变温度（TC）以下和以上截然不同的二维（2D）临界指数。该系统在TC以下表现出2D Ising型临界指数，在TC以上表现出2D XY型临界指数。相比之下，预期DMI效应较弱的同构Cl和中心对称Br类似物则表现出对称的2D临界行为。这些结果凸显了DMI在(C7H9NBr)2CuBr4中作为对称性破缺微扰的关键作用，它以上下不同的方式改变了TC两侧的磁临界行为。我们的研究是迄今未报道过的非对称2D临界行为在结构柔性和维度可调杂化钙钛矿中的实验实现。
英文摘要：
The possibility of different critical exponents on two sides of a magnetic transition has been theoretically predicted [PRB 13, 2222 (1976), PRL 115, 200601 (2015)] and experimentally realized [PRL 128, 015703 (2022)] in three-dimensional systems. However, the emergence of such a scenario in two dimensions is not yet established. Here, we report distinct two-dimensional (2D) critical exponents below and above the magnetic transition temperature (TC) through critical scaling analysis in a quasi-2D non-centrosymmetric, Dzyaloshinskii-Moriya interaction (DMI) active hybrid perovskite (C7H9NBr)2CuBr4. The system exhibits critical exponents of 2D Ising-type below TC and 2D XY-type above TC . In contrast, isostructural Cl and centrosymmetric Br analogs, in which the DMI effect is expected to be weaker, exhibit symmetric 2D critical behavior. These results highlight the crucial role of DMI in (C7H9NBr)2CuBr4 as a symmetry-breaking perturbation that alters the magnetic critical behavior differently above and below TC . Our study is the experimental realization of hitherto unreported asymmetric 2D critical behavior in structurally flexible and dimensionally tunable hybrid perovskites.
