Stabilizing the magnetic moment of single holmium atoms by symmetry
Stabilizing the magnetic moment of single holmium atoms by symmetry
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DOI：
10.1038/nature12759
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发表时间：
2013-11-14
期刊：
影响因子：
64.8
通讯作者：
Wulfhekel, Wulf
中科院分区：
文献类型：
--
作者：
Miyamachi, Toshio;Schuh, Tobias;Wulfhekel, Wulf
由于在高密度磁数据存储和作为量子计算平台方面的潜在用途，在非磁性表面上的单个磁性原子及其组装最近引起了人们的注意(1-8)。由它们的量子力学性质产生的一个基本问题是，这些原子的局域磁矩很容易受到与电子的相互作用、核自旋和衬底的晶格振动的不稳定(3-5)。即使施加大磁场来稳定磁矩，观测到的寿命仍然相当短(5，6)(不到一微秒)。已经提出了几种稳定磁矩的方法，例如在磁原子和衬底之间使用薄的绝缘层来抑制与衬底的传导电子(2，3，5)的相互作用，或者将几个磁矩耦合在一起以减少它们的量子力学涨落(7，8)。在这里，我们证明了在高导电性的金属衬底上单个Ho原子的磁矩可以达到分钟量级的寿命。从电子、核自旋和晶格振动的热浴中实现必要的去耦合是通过系统固有的几个对称性的显著组合实现的：时间反转对称性、总角动量的内部对称性和磁原子局域环境的点对称性。
Single magnetic atoms, and assemblies of such atoms, on nonmagnetic surfaces have recently attracted attention owing to their potential use in high-density magnetic data storage and as a platform for quantum computing(1-8). A fundamental problem resulting from their quantum mechanical nature is that the localized magnetic moments of these atoms are easily destabilized by interactions with electrons, nuclear spins and lattice vibrations of the substrate(3-5). Even when large magnetic fields are applied to stabilize the magnetic moment, the observed lifetimes remain rather short(5,6) (less than a microsecond). Several routes for stabilizing the magnetic moment against fluctuations have been suggested, such as using thin insulating layers between the magnetic atom and the substrate to suppress the interactions with the substrate's conduction electrons(2,3,5), or coupling several magnetic moments together to reduce their quantum mechanical fluctuations(7,8). Here we show that the magnetic moments of single holmium atoms on a highly conductive metallic substrate can reach lifetimes of the order of minutes. The necessary decoupling from the thermal bath of electrons, nuclear spins and lattice vibrations is achieved by a remarkable combination of several symmetries intrinsic to the system: time reversal symmetry, the internal symmetries of the total angular momentum and the point symmetry of the local environment of the magnetic atom.