Molecular magnetic hysteresis at 60 kelvin in dysprosocenium
Molecular magnetic hysteresis at 60 kelvin in dysprosocenium
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DOI：
10.1038/nature23447
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发表时间：
2017-08-24
期刊：
影响因子：
64.8
通讯作者：
Mills, David P.
中科院分区：
文献类型：
--
作者：
Goodwin, Conrad A. P.;Ortu, Fabrizio;Mills, David P.
稀土元素在分子和原子尺度的量子信息处理和高密度数据存储方面的潜在应用已被广泛研究。实验成就包括读取和操纵单个核自旋(1，2)，利用原子钟跃迁获得稳健的量子比特(3)，以及最近在单个原子中的磁性数据存储(4，5)。单分子磁体表现出分子起源的磁滞(6)--磁记忆效应和数据存储的先决条件--到目前为止，镧系元素的例子在最高温度下表现出这种现象。然而，自从单分子磁体被发现以来的近25年里，磁滞温度已经从4开尔文增加到大约14开尔文(8-10)，使用大约每秒20欧尔斯特德的恒定磁场扫描速度，尽管通过使用非常快的扫描率(11，12)(例如，30开尔文，每秒200欧尔斯特德)(12)实现了更高的温度(12)。在这里，我们报道了一个六叔丁基异氰酸酯配合物-[Dy(Cp-TTT)(2)][B(C6F5)(4)]，Cp-TTT={(C5H2Bu3)-Bu-t-1，2，4}和Bu-t=C(CH3)(3)-它在高达60Kelvin的温度下以22Oersted/s的扫描速度表现出磁滞。我们观察到在此温度下的弛豫动力学发生了明显的变化，这种变化持续存在于磁稀释的样品中，这表明磁滞现象的起源是非配位体独有的局域金属-配体振动模式。自旋动力学的从头计算表明，高温下的磁弛豫是由分子的局域振动引起的。这些结果表明，有了明智的分子设计，单分子在液氮以上温度下的磁性数据存储应该是可能的。
Lanthanides have been investigated extensively for potential applications in quantum information processing and high-density data storage at the molecular and atomic scale. Experimental achievements include reading and manipulating single nuclear spins(1,2), exploiting atomic clock transitions for robust qubits(3) and, most recently, magnetic data storage in single atoms(4,5). Single-molecule magnets exhibit magnetic hysteresis of molecular origin(6)-a magnetic memory effect and a prerequisite of data storage-and so far lanthanide examples have exhibited this phenomenon at the highest temperatures. However, in the nearly 25 years since the discovery of single-molecule magnets(7), hysteresis temperatures have increased from 4 kelvin to only about 14 kelvin(8-10) using a consistent magnetic field sweep rate of about 20 oersted per second, although higher temperatures have been achieved by using very fast sweep rates(11,12) (for example, 30 kelvin with 200 oersted per second)(12). Here we report a hexa-tert-butyldysprosocenium complex-[Dy(Cp-ttt)(2)][B(C6F5)(4)], with Cp-ttt = {(C5H2Bu3)-Bu-t-1,2,4} and Bu-t = C(CH3)(3)-which exhibits magnetic hysteresis at temperatures of up to 60 kelvin at a sweep rate of 22 oersted per second. We observe a clear change in the relaxation dynamics at this temperature, which persists in magnetically diluted samples, suggesting that the origin of the hysteresis is the localized metal-ligand vibrational modes that are unique to dysprosocenium. Ab initio calculations of spin dynamics demonstrate that magnetic relaxation at high temperatures is due to local molecular vibrations. These results indicate that, with judicious molecular design, magnetic data storage in single molecules at temperatures above liquid nitrogen should be possible.