论文标题
用于吸附的氦单层研究的超导型氯倍量
Superconducting Niobium Calorimeter for Studies of Adsorbed Helium Monolayers
论文作者
论文摘要
我们开发了一个由超导型niobium（NB）制成的真空容器的热量表，以研究吸附在石墨上的氦气单层，该单层是原型的二维量子问题，低于1K。Nb之所以选择，是因为其在超导状态中具有小的特异性热量。当底物的特定表面积很小时，降低附录热容量（$ c _ {\ rm {ad}} $）至关重要。在这里，我们显示了$ c _ {\ rm {ad}}的设计，构造和结果的详细信息，nb量热仪的测量值降至40 mk。 The measured $C_{\rm{ad}}$ was sufficiently small so that we can use it for heat capacity measurements on helium monolayers in a wide temperature range below 1 K. We found a relatively large excess heat capacity in $C_{\rm{ad}}$, which was successfully attributed to atomic tunneling of hydrogen (H) and deuterium (D) between trap centers near NB中的氧或氮杂质。通过将数据拟合到隧道模型来推导的H和D的隧道频率与掺杂H或D的NB的先前实验一致。
We developed a calorimeter with a vacuum container made of superconducting niobium (Nb) to study monolayers of helium adsorbed on graphite which are prototypical two-dimensional quantum matters below 1 K. Nb was chosen because of its small specific heat in the superconducting state. It is crucially important to reduce the addendum heat capacity ($C_{\rm{ad}}$) when the specific surface area of substrate is small. Here we show details of design, construction and results of $C_{\rm{ad}}$ measurements of the Nb calorimeter down to 40 mK. The measured $C_{\rm{ad}}$ was sufficiently small so that we can use it for heat capacity measurements on helium monolayers in a wide temperature range below 1 K. We found a relatively large excess heat capacity in $C_{\rm{ad}}$, which was successfully attributed to atomic tunneling of hydrogen (H) and deuterium (D) between trap centers near oxygen or nitrogen impurities in Nb. The tunnel frequencies of H and D deduced by fitting the data to the tunneling model are consistent with the previous experiments on Nb doped with H or D.
