MPI-CPfS co-workers: R. Kuechler, M. Brando, F. Steglich
During recent years we have designed, built and patented a new miniature capacitive dilatometer that can fit into a dilution refrigerator as well as into a commercial PPMS. The device is suitable for thermal expansion and magnetostriction measurements from 300 to about 0.03K and in magnetic fields up to 30 T, with a very high resolution of 0.02Å at low temperatures. The main body of the dilatometer is fabricated from a single block of a Be-Cu alloy by electrical discharge milling. The sample is clamped between the two plates of a capacitor whose capacitance changes when the sample expands or contracts. This change in capacitance can be measured very accurately with a commercially available capacitance bridge. Moreover, using a piezoelectric rotator the dilatometer can be rotated 360° inside an inner vacuum chamber of 40mm diameter.
The dilatometer for a dilution refrigerator (left) and for a PPMS (right). This dilatometer enables to measure changes in length of appromimately 0.02Ȧ, (one hundred times smaller than the separations of the atoms in a typical crystal) at temperatures between 300 and 0.03 K and magnetic fields as high as 30 T.