Evidence for strong correlations at finite temperatures in the dimerized magnet Na2Cu2TeO6
Evidence for strong correlations at finite temperatures in the dimerized magnet Na2Cu2TeO6
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二聚磁体 Na2Cu2TeO6 在有限温度下强相关性的证据
DOI：
10.1103/physrevb.104.224430
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发表时间：
2021
影响因子：
3.7
通讯作者：
Wen Jinsheng
中科院分区：
文献类型：
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作者：
Shangguan Yanyan;Bao Song;Dong Zhao-Yang;Cai Zhengwei;Wang Wei;Huang Zhentao;Ma Zhen;Liao Junbo;Zhao Xiaoxue;Kajimoto Ryoichi;Iida Kazuki;Voneshen David;Yu Shun-Li;Li Jian-Xin;Wen Jinsheng
形成交替海森堡链的二聚体磁铁表现出量子相干性和纠缠性，因此可以在量子信息和计算中找到潜在的应用。然而，磁性系统通常在有限温度下发生热退相干。在这里，我们展示了在交替的反铁磁-铁磁链化合物上的非弹性中子散射结果，激发的准粒子可以抵消热退相干并在高温下保持强相关性。在低温下，我们观察到沿着结晶轴形成的二聚体产生了清晰的分散的单重态-三重态激发。激振间隙很小，带宽约为激振间隙的一半。带顶能量沿[100]方向有微弱调制，表明链间耦合较小。随着温度的升高，间隙增大而带宽减小，导致三plons的可用相空间大幅减小。因此，随着温度的升高，洛伦兹型能量展宽变得高度不对称。这些结果与由硬核约束和准粒子相互作用产生的强相关态有关。我们认为这些结果不仅是在有限温度下强相关的证据，而且是在广泛的量子磁系统中强相关态的普遍性的证据。
Dimerized magnets forming alternating Heisenberg chains exhibit quantum coherence and entanglement and thus can find potential applications in quantum information and computation. However, magnetic systems typically undergo thermal decoherence at finite temperatures. Here, we show inelastic neutron scattering results on an alternating antiferromagnetic-ferromagnetic chain compoundthat the excited quasiparticles can counter thermal decoherence and maintain strong correlations at elevated temperatures. At low temperatures, we observe clear dispersive singlet-triplet excitations arising from the dimers formed along the crystallineaxis. The excitation gap is ofand the bandwidth is about half of the gap. The band top energy has a weak modulation along the [100] direction, indicative of a small interchain coupling. The gap increases while the bandwidth decreases with increasing temperature, leading to a strong reduction in the available phase space for the triplons. As a result, the Lorentzian-type energy broadening becomes highly asymmetric as the temperature is raised. These results are associated with a strongly correlated state resulting from hard-core constraint and quasiparticle interactions. We consider these results to be not only evidence for strong correlations at finite temperatures in, but also for the universality of the strongly correlated state in a broad range of quantum magnetic systems.