CPM Seminar

Method for cooling nanoelectronic samples to microkelvin temperatures

Kai Schwarzw�lder

University of Basel

A new scheme aimed at cooling nanoelectronic samples to microkelvin temperatures is presented. Each measurement lead of the set-up includes a separate nuclear adiabatic demagnetisation refrigerator, thereby placing the circuit into direct electrical and thermal contact with a reservoir at microkelvin temperatures.

We have designed, built, and tested a prototype incorporating our novel scheme, including sintered silver heat exchangers for precooling (located in the mixing chamber), superconducting Aluminium heat switches, ~0.5 mol of Copper in each lead for demagnetisation and a home built chip carrier allowing direct wire-bonding from the leads to the sample. Bulk electron temperatures in the Copper pieces of ~1 mK have been achieved, thus completing the first steps towards ultracold nanostructures.