Thermal and Magnetic Properties of Thin Film Topological Insulators

In this study, we investigate the electronic, magnetic, and thermodynamic properties of a thin film made from topological insulator (TI) material exhibiting structure inversion asymmetry. Our results reveal that the energy obtained by diagonalizing the thin‐film Hamiltonian model is influenced by an external uniform magnetic field, oriented perpendicular to the substrate, as well as by the Rashba field. The resulting Landau level energy spectra are thoroughly analyzed, with a detailed investigation of the effects of hybridization and exchange interactions on these levels. Our findings reveal level crossings for different values of the exchange constant, Rashba coupling strength, and applied potential. Additionally, we explore the variations in the density of states as functions of energy and magnetic field strength. The Fermi energy fluctuations, at a fixed electron concentration, are computed as a function of the applied magnetic field. Our results demonstrate that by tuning the strength of the Rashba coupling, hybridization, and exchange interactions, the thin film can be controlled to exhibit either a conventional insulator or a TI. Employing well‐established statistical physics relations, we determine the partition function, ensure convergence, and calculate the average energy of the material. Notably, the magnetic susceptibility exhibits characteristic oscillatory peaks as a function of the inverse magnetic field, a signature of the de Haas–van Alphen effect in topological thin films under an external perpendicular magnetic field. Depending on the strength of the magnetic field, the material can exhibit either ferromagnetic or paramagnetic behavior. Furthermore, we evaluate the magnetocaloric impact across a range of temperatures and exchange interaction strengths due to the ferromagnetic substrate. Our study provides deeper insights into the interplay between Rashba spin–orbit coupling (RSOC), exchange interactions, and external magnetic fields in governing the electronic, magnetic, and thermal properties of thin film systems. Furthermore, our findings indicate that these thin films have potential applications in a wide range of technological fields, such as spintronics, valleytronics, and magnetocaloric.