Clamping effects in the Al_(2)O_(3)(1120)/Nb(110)/Eu(110) epitaxial system

摘要

In-plane and out-of-plane lattice parameters of Nb and Eu have been measured as a function of temperature between 10 and 300 K in the Al_(2)O_(3)(1120)/Nb(110)/Eu(110) epitaxial system. It is shown that the Nb lattice is clamped in the growth plane to the sapphire substrate, in the whole temperature range. On its own, the Eu lattice is totally free to expand isotropically above a clamping temperature T_(cl), below which in-plane parameters also freeze to an almost constant value. This well-defined clamping temperature strongly depends on the Eu thickness and likely is related to the thermal mobility of interface defects.