Superheating nature coupled with Mg‐doping effect of high thermal stable NdBa2Cu3O7‐δ film

NdBa2Cu3O7‐δ thin film deposited on a MgO substrate has been verified to remain solid above its peritectic melting temperature (Tp). Such a superheating nature is attributed to its low energy surface and epitaxial interface with substrate. Here, combining superheating nature with doping effect, we report a novel structure, Mg‐doped NdBa2Cu3O7‐δ film with YBa2Cu3O7‐δ buffer layer for the first time. Remarkably, this film presents a higher thermal stability level than heretofore possible when acting as a seed for preparing SmBa2Cu3O7‐δ bulks by melt growth, enduring a temperature of 1128°C, 43 K above its Tp for 1 hour. The utilization of such a high Tmax in melt growth is beneficial to the fabrication of large‐sized and high‐performance bulk in terms of effectively broadening the growth window and suppressing the heterogeneous nucleation. More importantly, some high thermal stability required technological applications, such as batch growth and failed bulk recycling, are likely to be realized by this novel Mg‐doped NdBa2Cu3O7‐δ film seed. Finally, we show how the observed metastable phase is linked to the distinctive film architecture. We report a novel structure, the Mg‐doped NdBa2Cu3O7‐δ film with the YBa2Cu3O7‐δ buffer layer for the first time. The thermal stability of this film is superior to all the practically used seed materials, capable of enduring a high processing temperature of 1128°C (42K above its Tp), when inducing SmBa2Cu3O7‐δ bulks in top‐seeded melt‐growth.