Promoting Surface Conduction through Scalable Structure Engineering of Flexible Topological Insulator Thin Films

• Type: Article in International Scientific Journal
• Date: 2024

Authors

Moreira, M (Author) Other; Pires, AL (Author) Other; Ferreira-Teixeira, S (Author) Other; Iurkevich, O (Author) Other; Vilarinho, R (Author) Other; Eduardo V Castro (Author) FCUP; pereira, a. m. (Author) FCUP

Journal

The Journal is awaiting validation by the Administrative Services.

Title: ADVANCED FUNCTIONAL MATERIALS

ISSN: 1616-301X

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Other information

Authenticus ID: P-016-XP5

DOI: 10.1002/adfm.202405057

Abstract (EN): Spintronics, micro/nanofabrication, and the semiconductor industry are undergoing significant transformations, highlighting the need for flexible technologie. This study examines the possibility of integrating topological insulators (TIs), specifically Bi2Te3 thin films (13-191 nm), into flexible spintronic applications through scalable magneto-sputtering techniques, and investigates how structural organization influences electrical and topological properties through post-thermal annealing. Films annealed above 250 degrees C display improved polycrystalline structure, larger crystallites, fewer local defects, and higher a room-temperature Seebeck coefficient (S) and resistivity (rho), suggesting decreased bulk electronic contributions. A metastable transport regime is identified in the temperature-dependent resistivity of films annealed at 300 degrees C between 20-100 K; in this range, the thinnest film exhibits markedly metallic behavior, signaling the presence of topological surface states (TSS). Magnetoresistance measurements of as-grown and annealed films, between 3-20 K, demonstrate weak antilocalization. Applying the Hikami-Larkin-Nagaoka model, alpha-coefficients are found to scale with thickness from 0.5-1, indicating thickness-controlled coupling of the TSS. Post-annealing at 300 degrees C, the phase coherence length, L phi, of the thinner films increases, while the temperature dephasing rate shifts from similar to 0.7 (as-grown) to similar to 0.5 (post-annealing), aligning with expected values for 2D TSS. These are encouraging findings for large-scale manufacturing flexible TI technologies, without sacrificing tunabilit. This study pioneers the integration of Bi2Te3 topological insulators into flexible substrates, through DC magneto-sputtering and thermal annealing. The flexible thin films show compelling evidence of topological conduction. Remarkably, annealing enhances magnetoresistance, aligning it perfectly with Hikami-Larkin-Nagaoka predictions for weak antilocalization, suggesting improved topological conduction through innovative structural engineering. This breakthrough paves the way for promising advances in flexible spintronics. image

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 13