Abstract
We demonstrate both theoretically and experimentally two limiting factors in cooling electrons using biased tunnel junctions to extract heat from a normal metal into a superconductor. First, when the injection rate of electrons exceeds the internal relaxation rate in the metal to be cooled, the electrons do not obey the Fermi-Dirac distribution, and the concept of temperature cannot be applied as such. Second, at low bath temperatures, states within the gap induce anomalous heating and yield a theoretical limit of the achievable minimum temperature.
| Original language | English |
|---|---|
| Article number | 056804 |
| Pages (from-to) | 1-4 |
| Number of pages | 4 |
| Journal | Physical Review Letters |
| Volume | 92 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 6 Feb 2004 |
| MoE publication type | A1 Journal article-refereed |
Keywords
- cooling electron
- superconductor
- tunnel junction