Functional oxides attract significant attention due to their wide range of properties including superconductivity, ferroelectricity, ferromagnetism, and multiferroicity. This plethora of properties arises from the strong interactions between charge, orbital, spin, and structural properties, leading to a wide range of functionalities. Among functional oxides, perovskites stand out as one of the most versatile thanks to their integrability as thin-films with silicon-based electronic devices, making them suitable for applications ranging from memory transistors and memory devices to optical circuits, from sensors to transducers [1]. In addition to the intrinsic properties of the bulk crystals, the possibility of nanostructuring them in a thin-film fashion makes them perfect candidates for integration into electronics and it opens a further degree of freedom to control some of their properties [2]. However, the thermal behavior of this family of materials, specifically as thin-films, has not been fully investigated yet.
In this work, the thermal properties of suspended oxide perovskite membranes with varying thicknesses are studied. Specifically, suspended SrTiO3 films, with thickness between 30 and 100 nm, that were epitaxially grown onto a sacrificial layer of Sr3Al2O6 using the pulsed laser deposition technique [3]. First, the films were transferred to a substrate with patterned holes to suspend them and to study the evolution of the phonon modes by Raman spectroscopy as a function of temperature (between 20 K and 300 K), as phonons are the fingerprint of the phase transition (from a cubic to a tetragonal). Secondly, a study of the dependence of the thermal conductivity on temperature (also from 20 K to 300 K) was conducted using a combination of the thermal bridge method [4] and the three probe technique [5], using a scanning laser as a heat source to correct for contact resistance. Finally, the experimental results were corroborated by second-principles density-functional theory calculations.
This combination of Raman spectroscopy and electro-thermal measurements allows to relate the thermal properties with the phase-changes of the studied thin-films, highlighting the impact of structural phase transitions on their thermal behavior. Understanding these effects is key to optimize the integration of functional oxide thin films in novel advanced electronic devices.
[1] L. Han, Adv. Funct. Mater. 2024, 34, 2309543.
[2] F. M. Chiabrera, ANNALEN DER PHYSIK, 2022, 534, 2200084.
[3] G. Segantini, Nano Letters, 2024, 24 (45), 14191-14197.
[4] Y. Kaur, ACS Applied Materials & Interfaces 2025, 17 (1), 1883-1891.
[5] D. Liu, Nano Letters, 2014, 14 (2), 806-812.