arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2012.08722cond-mat.str-elcond-mat.supr-con
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Kagome晶格化合物中无序诱导的类自旋液体行为

Disorder-induced spin-liquid-like behavior in kagome-lattice compounds

Zhen Ma, Zhao-Yang Dong, Si Wu, Yinghao Zhu, Song Bao, Zhengwei Cai, Wei Wang, Yanyan Shangguan, Jinghui Wang, Kejing Ran, Dehong Yu, Guochu Deng, Richard A. Mo… 展开作者

Zhen Ma, Zhao-Yang Dong, Si Wu, Yinghao Zhu, Song Bao, Zhengwei Cai, Wei Wang, Yanyan Shangguan, Jinghui Wang, Kejing Ran, Dehong Yu, Guochu Deng, Richard A. Mole, Hai-Feng Li, Shun-Li Yu, Jian-Xin Li, Jinsheng Wen

摘要:

量子自旋液体(QSL)是一种奇异的物质状态,受到广泛的研究。然而,泛在无序与量子SL行为之间的关系尚不清楚。在这里,通过对两个kagomé晶格QSL候选物Tm $_3$ Sb $_3$ Zn $_2$ O $_{14}$和Tm $_3$ Sb $_3$ Mg $_2$ O $_{14}$进行比较实验研究,这两个候选物彼此同构,但分别具有强和弱的结构无序,我们明确地表明,无序可以诱导类似自旋液体的特征。特别是,两种化合物都显示出主要的反铁磁相互作用,Tm $_3$ Sb $_3$ Zn $_2$ O $_{14}$和Tm $_3$ Sb $_3$ Mg $_2$ O $_{14}$的居里-外斯温度分别为-17.4和-28.7 K,但在低至约0.05 K时仍保持无序。比热的结果表明,存在的无间隙的磁激励,其特征在于由一个剩余的线性项。用非弹性中子散射(INS)方法得到的低温磁激发谱具有宽的连续谱。所有这些观察结果都与QSL的观察结果一致。然而,我们发现,在Tm $_3$ Sb $_3$ Zn $_2$ O $_{14}$,它具有很强的无序从随机混合的磁性Tm $^{3+}$和Zn-Zn $^{2+}$,在比热和INS测量中观察到的低能量磁激发大大增强,相比,Tm $_3$ Sb $_3$ Mg $_2$ O $_{14}$,其中有少得多的无序。我们认为Zn $^{2+}$ /Mg $^{2+}$中Tm $^{3+}$离子的有效自旋引起低能磁激发,而随机占据的量决定了激发强度.这些结果提供了直接的证据,模仿的QSL引起的障碍。

英文摘要:

Quantum spin liquids (QSLs) are an exotic state of matter that is subject to extensive research. However, the relationship between the ubiquitous disorder and the QSL behaviors is still unclear. Here, by performing comparative experimental studies on two kagomé-lattice QSL candidates, Tm$_3$Sb$_3$Zn$_2$O$_{14}$ and Tm$_3$Sb$_3$Mg$_2$O$_{14}$, which are isostructural to each other but with strong and weak structural disorder, respectively, we show unambiguously that the disorder can induce spin-liquid-like features. In particular, both compounds show dominant antiferromagnetic interactions with a Curie-Weiss temperature of -17.4 and -28.7 K for Tm$_3$Sb$_3$Zn$_2$O$_{14}$ and Tm$_3$Sb$_3$Mg$_2$O$_{14}$, respectively, but remain disordered down to about 0.05 K. Specific heat results suggest the presence of gapless magnetic excitations characterized by a residual linear term. Magnetic excitation spectra obtained by inelastic neutron scattering (INS) at low temperatures display broad continua. All these observations are consistent with those of a QSL. However, we find in Tm$_3$Sb$_3$Zn$_2$O$_{14}$ which has strong disorder resulting from the random mixing of the magnetic Tm$^{3+}$ and nonmagnetic Zn$^{2+}$, that the low-energy magnetic excitations observed in the specific heat and INS measurements are substantially enhanced, compared to those of Tm$_3$Sb$_3$Mg$_2$O$_{14}$ which has much less disorder. We believe that the effective spins of the Tm$^{3+}$ ions in the Zn$^{2+}$/Mg$^{2+}$ sites give rise to the low-energy magnetic excitations, and the amount of the random occupancy determines the excitation strength. These results provide direct evidence of the mimicry of a QSL caused by disorder.

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