Fermionic response from fractionalization in an insulating two-dimensional magnet
Fermionic response from fractionalization in an insulating two-dimensional magnet
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DOI：
10.1038/nphys3809
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发表时间：
2016-10-01
期刊：
影响因子：
19.6
通讯作者：
Moessner, R.
中科院分区：
文献类型：
--
作者：
Nasu, J.;Knolle, J.;Moessner, R.
常规有序磁体具有玻色子元激发，称为磁振子。相比之下，在一维以上的磁绝缘体中，没有一个已知的磁绝缘体的激发不是玻色子，而是费米子。理论上，一些量子自旋液体（QSL）（1）-当量子涨落排除有序状态时可能出现的新拓扑相-已知将马约拉纳费米子（2）表现为自旋（3）的分形产生的准粒子。唉，尽管进行了大量的研究，他们的实验观察仍然难以捉摸。在这里，我们表明，在二维材料α-RuCl 3的宽能量和温度范围内，实验拉曼散射数据（4）中的费米子激发非常直接明显。这表明磁性材料作为马约拉纳费米子宿主的重要性。反过来，这第一个系统的评价在有限温度下的QSL的动力学强调的作用，激发态检测这种奇异的属性，否则难以识别的拓扑QSL。
Conventionally ordered magnets possess bosonic elementary excitations, called magnons. By contrast, no magnetic insulators in more than one dimension are known whose excitations are not bosons but fermions. Theoretically, some quantum spin liquids (QSLs)(1)- new topological phases that can occur when quantum fluctuations preclude an ordered state-are known to exhibit Majorana fermions(2) as quasiparticles arising from fractionalization of spins(3). Alas, despite much searching, their experimental observation remains elusive. Here, we show that fermionic excitations are remarkably directly evident in experimental Raman scattering date(4) across a broad energy and temperature range in the two-dimensional material alpha-RuCl3. This shows the importance of magnetic materials as hosts of Majorana fermions. In turn, this first systematic evaluation of the dynamics of a QSL at finite temperature emphasizes the role of excited states for detecting such exotic properties associated with otherwise hard-to-identify topological QSLs.