Thermal expansion of magnetic metals at low temperatures

TLDR

Abstract

Measurements have been made from 2 to 30 °K and 60 to 90 °K of the thermal expansion of iron, cobalt and nickel, which show that the Grüneisen parameter γl for the lattice decreases slightly at low temperatures and that the electronic parameter γe (calculated from the ratio of the electronic contributions to expansion and heat capacity) is about 2.2. Similar measurements below 30 °K on α-manganese, chromium, face-centred cubic iron-nickel (35-50% Ni) alloys, and Fe0 5 Mn0 5 indicate a negative term, proportional to T, in the expansion coefficient. This is particularly large in Invar and in α-manganese. For γ-manganese (+15% Cu) no negative term is observed in the expansion. Results are discussed in terms of electronic and magnetic contributions.