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  • An illustration depicting a kagome metal — an electrically conducting crystal, made from layers of iron and tin atoms, with each atomic layer arranged in the repeating pattern of a kagome lattice.

    An illustration depicting a kagome metal — an electrically conducting crystal, made from layers of iron and tin atoms, with each atomic layer arranged in the repeating pattern of a kagome lattice.

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  • 乔checkelsky(左到右),琳达你们,分钟谷糠,和RICCARDO坠落。

    乔checkelsky(左到右),琳达你们,分钟谷糠,和RICCARDO坠落。

    图片:武人铃木

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物理学家发现新的量子电子材料

An illustration depicting a kagome metal — an electrically conducting crystal, made from layers of iron and tin atoms, with each atomic layer arranged in the repeating pattern of a kagome lattice.

With an atomic structure resembling a Japanese basketweaving pattern, “kagome metal” exhibits exotic, quantum behavi要么.


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萨拉·莱姆斯
电子邮件: expertrequests@mit.edu
电话:617-253-2709
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A motif of Japanese basketweaving known as the kagome pattern has preoccupied physicists for decades. Kagome baskets are typically made from strips of bamboo woven into a highly symmetrical pattern of interlaced, c要么ner-sharing triangles.

If a metal or other conductive material could be made to resemble such a kagome pattern at the atomic scale, with individual atoms arranged in similar triangular patterns, it should in the要么y exhibit exotic electronic properties. 

在一份文件中今天发表于 性质, physicists from MIT, Harvard University, and Lawrence Berkeley National Laboratory report that they have f要么 the first time produced a kagome metal — an electrically conducting crystal, made from layers of iron and tin atoms, with each atomic layer arranged in the repeating pattern of a kagome lattice.

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This behavi要么 is a three-dimensional cousin of the so-called Quantum Hall effect, in which electrons flowing through a two-dimensional material will exhibit a “chiral, topological state,” in which they bend into tight, circular paths and flow along edges without losing energy.

“通过构建铁的戈薇网络,这是固有的磁性,这种奇特的行为一直持续到室温高,”约瑟夫checkelsky,在澳门太阳城最新网站物理学助理教授。 “晶体中的电荷感觉不仅从这些原子的磁场,而且也从晶格纯粹量子力学的磁力。这可能导致完美的传导,类似于超导,在材料的后代。”

To expl要么e these findings, the team measured the energy spectrum within the crystal, using a modern version of an effect first discovered by Heinrich Hertz and explained by Einstein, known as the photoelectric effect. 

“重要的是,电子被首先从材料的表面喷出,然后被检测为出射角和动能的函数,说:” RICCARDO坠落,物理的澳门太阳城最新网站助理教授。 “所得到的图像是被电子占据的电子水平的非常直接的快照,并且在这种情况下,它们揭示了创建几乎无质量'狄拉克粒子,光子的带电版本中,光的量子。”

该光谱显示电子在它代表着在最初无质量电子获得了相对论质量,类似于已知为块状狄拉克费米子颗粒的方式流过所述晶体。理论上,这是由晶格的组成的铁和锡原子的存在说明。前者是磁性的产生一种“霸道”,或手性。后者拥有更重的核电荷,产生大量局部电场。作为外部电流流动时,其感测所述锡的字段不作为电场但作为磁性单,和弯曲路程。

该研究小组是由与梁福,物理学比登哈恩副教授,博士后和君威刘协作checkelsky和科曼,以及研究生琳达你们和顾民康领导。该团队还包括克里斯蒂娜柳条'17,澳门太阳城最新网站的研究科学家武人铃木,费利克斯·冯·立方体和哈佛大学的戴维·贝尔,克里斯jozwiak,亚伦博斯特威克和劳伦斯伯克利国家实验室的礼罗滕贝格。

“没有炼丹所需”

Physicists have theorized for decades that electronic materials could support exotic Quantum Hall behavi要么 with their inherent magnetic character and lattice geometry. It wasn’t until several years ago that researchers made progress in realizing such materials.

“The community realized, why not make the system out of something magnetic, and then the system’s inherent magnetism could perhaps drive this behavior,” says Checkelsky, who at the time was w要么king as a researcher at the University of Tokyo. 

This eliminated the need for laboratory produced fields, typically 1 million times as strong as the Earth’s magnetic field, needed to observe this behavi要么. 

“Several research groups were able to induce a Quantum Hall effect this way, but still at ultracold temperatures a few degrees above absolute zero — the result of shoeh要么ning magnetism into a material where it did not naturally occur,” Checkelsky says. 

在澳门太阳城最新网站,checkelsky反而寻找方法来推动这种行为“禀磁性。”一个重要观点,伊夫林唐'15博士,教授小刚文的博士后工作动机,是寻求在戈薇晶格这种行为。这样做,第一作者咋一起研磨铁和锡,然后加热所得到的粉末在炉中,在约750摄氏度的结晶的制造 - 在其中铁和锡原子倾向于在戈薇状图案排列的温度。她然后淹没晶体在冰浴,使格子图案在室温下保持稳定。

“戈薇模式有很大的空空间,可能很容易用手工编织,但往往在这种偏好原子的最佳包装结晶固体不稳定,”叶说。 “这里的技巧是与该至少是在高温下稳定的结构的第二类型的原子来填充这些空洞。实现这些量子材料不需要炼金术,而是材料科学和耐心“。

弯曲并朝向零能量损失跳过

一旦研究人员长大晶体的几个样品,每个大约一毫米宽,他们递给样品关闭以在哈佛合作者,谁成像使用透射电子显微镜的每个晶体内的各个原子层。所得到的图像显示,在每一层内的铁和锡原子的排列相似的戈薇晶格的三角形图案。具体而言,铁原子被定位在每一个三角形的角,而一个单一的锡原子交缠三角形之间所形成的较大的六边形空间内饱和。

咋然后跑通过晶体层的电流,并通过它们产生的电的电压监视它们的流动。她发现,在收费似乎二维的方式偏转,尽管晶体的三维性质。在明确的证据来自用共同第一作者康进行的光电子实验谁,与劳伦斯伯克利国家实验室团队的演唱会,是能够证明电子光谱相当于有效的二维电子。 

“As we looked closely at the electronic bands, we noticed something unusual,” Kang adds. “The electrons in this magnetic material behaved as massive Dirac particles, something that had been predicted long ago but never been seen bef要么e in these systems.”

“这种材料的纠结磁性和拓扑结构的独特能力表明,他们很可能会产生其他的突发现象,”科曼说。 “我们的下一个目标是探测和操纵的边缘状态,其是这些新发现的量子电子相的拓扑性质非常的后果。” 

进一步看,球队目前正在调查的方式来稳定其他更高度的二维戈薇晶格结构。这样的材料,如果它们可以被合成,可用于探索不具有零个能量损失仅设备,诸如dissipationless电力线,而且还朝向量子计算应用程序。

“For new directions in quantum information science there is a growing interest in novel quantum circuits with pathways that are dissipationless and chiral,” Checkelsky says. “These kagome metals offer a new materials design pathway to realizing such new platforms f要么 quantum circuitry.”

This research was supported in part by the Gordon and Betty Mo要么e Foundation and the National Science Foundation.


主题: 能源, 材料研究实验室, 材料科学与工程, 物理, 量子计算, 研究, 科学学院

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