Toward single-atom memory
Toward single-atom memory
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DOI：
10.1126/science.aaf2481
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发表时间：
2016-04
期刊：
影响因子：
56.9
通讯作者：
A. Khajetoorians;A. Heinrich
中科院分区：
文献类型：
--
作者：
A. Khajetoorians;A. Heinrich
单个钬原子可以用作稳定的磁存储器[参见Donati等人的报告]。将信息存储在单原子磁体的集合中代表了数据存储技术的最终小型化，其中每个原子磁矩的两个特定方向代表一位（0或1）信息（见图，面板A）。使用单原子磁体的固有困境是保持它的磁化状态，或者换句话说，能够在没有外部磁场的情况下在实际温度下将信息保持在一个比特状态（1，2）。这种剩磁现象很难从单个原子中实现，部分原因是对环境波动的鲁棒性减弱可能会无意中翻转磁性状态，从而消除磁性记忆。最近试图观察单个原子中的剩磁（3）被证明是过早的，因为结果与该系统的磁基态（4）不相容，并且无法复制（4，5）。因此，单原子磁体的这一定义性质是否真的能够实现的问题至今仍是一个悬而未决的问题。在本期的第318页，Donati等人（6）证明了单个钬原子在高达40 K的温度下表现出剩磁，远远高于以前由3到12个原子组成的原子尺度磁体的记录（1，2，5）-这是任何磁体在尺寸和稳定性方面的记录。
Single holmium atoms can be used as a stable magnetic memory [Also see Report by Donati et al.] Storing information in an ensemble of single-atom magnets represents the ultimate miniaturization of data storage technology, in which two specific orientations of each atomic magnetic moment represent a bit (a 0 or 1) of information (see the figure, panel A). The inherent dilemma in using a single-atom magnet is keeping it magnetized—or, in other words, being able to hold the information in one of the bit states without an external magnetic field for a useful amount of time and at practical temperatures (1, 2). This phenomenon of magnetic remanence is dif cult to realize from a single atom, in part because diminished robustness against fluctuations from the environment can unintentionally flip the magnetic state, thus wiping out the magnetic memory. A recent attempt to observe remanence in a single atom (3) proved premature, as the results were incompatible with the magnetic ground state of that system (4) and could not be reproduced (4, 5). Hence, the question of whether this defining property of a single-atom magnet can actually be achieved has remained an open question until now. On page 318 of this issue, Donati et al. (6) demonstrate that single holmium atoms exhibit magnetic remanence up to temperatures of 40 K, much higher than previous records of atomic-scale magnets composed of 3 to 12 atoms (1, 2, 5)—a record in both size and stability for any magnet.