Superconducting aluminum heat switch with 3 nΩ equivalent resistance.
Superconducting aluminum heat switch with 3 nΩ equivalent resistance.
复制标题
超导铝热开关，等效电阻为 3 nΩ。
DOI：
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发表时间：
2021
影响因子：
1.6
通讯作者：
A. Fefferman
中科院分区：
文献类型：
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作者：
J. Butterworth;S. Triqueneaux;Š. Midlik;I. Golokolenov;A. Gerardin;Thibaut Gandit;G. Donnier;J. Goupy;M. K. Phuthi;D. Schmoranzer;E. Collin;A. Fefferman
超导热开关具有极低的正常状态电阻，是构建具有高冷却功率的连续核退磁制冷机所必需的。由于铝的高德拜温度和高纯度的商业可用性，铝是一种适合用于热开关的超导体。我们制造了一个高质量的铝热交换器，它的设计与以前的热交换器有很大的不同。为了以低接触电阻将Al与Cu结合，我们在不破坏电子束蒸发器真空的情况下，对Al进行等离子蚀刻，去除其氧化层，然后立即沉积Au。在热开关的正常状态下，我们测量到的热导率为8T W/K2，根据Wiedemann-Franz定律，这相当于3 nΩ的电阻。在超导状态下，我们在50 mK时测得的热导比正常状态低2 × 106倍。
Superconducting heat switches with extremely low normal state resistances are needed for constructing continuous nuclear demagnetization refrigerators with high cooling power. Aluminum is a suitable superconductor for the heat switch because of its high Debye temperature and its commercial availability in high purity. We have constructed a high quality Al heat switch whose design is significantly different than that of previous heat switches. In order to join the Al to Cu with low contact resistance, we plasma etched the Al to remove its oxide layer and then immediately deposited Au without breaking the vacuum of the e-beam evaporator. In the normal state of the heat switch, we measured a thermal conductance of 8T W/K2, which is equivalent to an electrical resistance of 3 nΩ according to the Wiedemann-Franz law. In the superconducting state, we measured a thermal conductance that is 2 × 106 times lower than that of the normal state at 50 mK.