HEAT-CAPACITY OF MULTILAYERS OF HE-3 ADSORBED ON GRAPHITE AT LOW MILLIKELVIN TEMPERATURES
HEAT-CAPACITY OF MULTILAYERS OF HE-3 ADSORBED ON GRAPHITE AT LOW MILLIKELVIN TEMPERATURES
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DOI：
10.1103/physrevb.41.1842
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发表时间：
1990-02-01
影响因子：
3.7
通讯作者：
GREYWALL, DS
中科院分区：
文献类型：
--
作者：
GREYWALL, DS
给出了He-3吸附在石墨上的精确热容计算结果。数据的温度范围从2到200mK，而覆盖范围从略低于单层完成到五个原子层。可以清楚地观察到原子被推进到第二、第三和第四层。对于无公度的亚单分子层固相，核-自旋交换能为数十分之一mK量级。这些值与最近从核磁共振实验中推断的值有很大不同。第二层流体的数据给出了3个准粒子有效质量，与相应的第一层值很好地吻合，范围从裸露的He 3质量的1到5倍。在第三层促进之前，第二层经历了一级相变。通过与第一层相图的比较，假定第二层中的新相为登记固体。现在登记的是第一层He 3，它继续以与石墨衬底不相称的三角形晶格固体存在。登记相在2.5MK处表现出一个大的、尖锐的热容异常。
Precise heat-capacity results are presented for He 3 adsorbed on graphite. The temperature range of the data is from 2 to 200 mK, while the coverages span from somewhat below monolayer completion up through five atomic layers. Promotion of atoms into the second, third, and fourth layers is clearly observed. Nuclear-spin exchange energies of the order of a few tenths of a mK are found for the submonolayer incommensurate solid phase. These values differ significantly from those recently inferred from NMR experiments. Data for the second-layer fluid yield He 3 quasiparticle effective masses that agree well with the corresponding first-layer values and range from one to five times the bare He 3 mass. Prior to third-layer promotion, the second layer undergoes a first-order phase transition. By comparison with the phase diagram for the first layer, the new phase in the second layer is assumed to be a registered solid. Registry is now with respect to the first He 3 layer, which continues to exist as a triangular-lattice solid incommensurate with the graphite substrate. The registered phase exhibits a large, sharp heat-capacity anomaly at 2.5 mK.