McCall S K, Fluss M J, Chung B W, McElfresh M W, Jackson D D, Chapline G F
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17179-83. doi: 10.1073/pnas.0608552103. Epub 2006 Nov 6.
Plutonium possesses the most complicated phase diagram in the periodic table, driven by the complexities of overlapping 5f electron orbitals. Despite the importance of the 5f electrons in defining the structure and physical properties, there is no experimental evidence that these electrons localize to form magnetic moments in pure Pu. Instead, a large temperature-independent Pauli susceptibility indicates that they form narrow conduction bands. Radiation damage from the alpha-particle decay of Pu creates numerous defects in the crystal structure, which produce a significant temperature-dependent magnetic susceptibility, chi(T), in both alpha-Pu and delta-Pu (stabilized by 4.3 atomic percent Ga). This effect can be removed by thermal annealing above room temperature. By contrast, below 35 K the radiation damage is frozen in place, permitting the evolution in chi(T) with increasing damage to be studied systematically. This result leads to a two-component model consisting of a Curie-Weiss term and a short-ranged interaction term consistent with disorder-induced local moment models. Thus, it is shown that self-damage creates localized magnetic moments in previously nonmagnetic plutonium.
钚具有元素周期表中最复杂的相图，这是由重叠的5f电子轨道的复杂性所驱动的。尽管5f电子在定义结构和物理性质方面很重要，但没有实验证据表明这些电子在纯钚中会定域形成磁矩。相反，一个与温度无关的大泡利磁化率表明它们形成了狭窄的导带。钚的α粒子衰变产生的辐射损伤在晶体结构中产生了大量缺陷，这在α-Pu和δ-Pu（由4.3原子百分比的镓稳定）中都产生了显著的与温度相关的磁化率χ(T)。这种效应可以通过在室温以上进行热退火来消除。相比之下，在35 K以下，辐射损伤被固定下来，从而可以系统地研究χ(T)随损伤增加的变化。这一结果导致了一个由居里-外斯项和一个与无序诱导的局域矩模型一致的短程相互作用项组成的双组分模型。因此，研究表明自损伤在以前无磁性的钚中产生了局域磁矩。
