Articolo in rivista, 2020, ENG, 10.1016/j.jmmm.2020.166885

Ferromagnetic resonance of Co thin films grown by atomic layer deposition on the Sb2Te3 topological insulator

Emanuele Longo (a,b), Claudia Wiemer (a), Matteo Belli (a), Raimondo Cecchini (a), Massimo Longo (a), Matteo Cantoni (c), Christian Rinaldi (c), Michael D. Overbeek (e), Charles H. Winter (e), Gianluca Gubbiotti (d), Graziella Tallarida (a), Marco Fanciulli (a,b), Roberto Mantovan (a)

(a) CNR-IMM, Unit of Agrate Brianza (MB), Via C. Olivetti 2, 20864 Agrate Brianza, MB, Italy (b) Università degli Studi di Milano-Bicocca, Dipartimento di Scienze dei Materiali, Via R. Cozzi 55, 20126 Milano, Italy (c) Dipartimento di Fisica, Politecnico di Milano, Via G. Colombo 81, 20131 Milano, Italy (d) Istituto Officina dei Materiali del CNR (CNR-IOM), Sede Secondaria di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia, Italy (e) Winter Laboratory, Wayne State University, 48202 Cass Ave, Detroit, MI, USA

Interfacing ferromagnetic materials with topological insulators is an intriguing strategy in order to enhance spin-to-charge conversion mechanisms, paving the way toward highly efficient spin-based electronic devices. In particular, the use of large-scale deposition techniques is demanding for a sustainable and cost-effective industrial technology transfer. In this work, we study the magnetic properties of the Co/Sb2Te3 heterostructure, where the ferromagnetic Co layer is deposited by atomic layer deposition on top of the Sb2Te3 topological insulator, which is grown by metal organic chemical vapor deposition. In particular, broadband ferromagnetic resonance is employed to characterize the Co/Sb2Te3 system and the reference Co/Pt heterostructure. For Co/Sb2Te3, we extract an effective magnetic anisotropy constant K = 4.26*10^6 erg / cm^3, which is an order of magnitude higher than in Co/Pt (Keff = 0.43*10^6 erg / cm^3). The large difference in the Keff values observed in Co/Sb2Te3 and Co/Pt is explained in terms of the different Co crystalline structures achieved on top of Sb2Te3 and Pt, respectively. Interestingly, the Co/Sb2Te3 system displays a relatively large Gilbert damping constant (? = 0.095), which we suggest as possibly due to spin pumping from the Co layer into the Sb2Te3 topological insulator.

Journal of magnetism and magnetic materials 509 , pp. 166885-1–166885-6

Keywords

Co, Sb2Te3, topological insulators, ferromagnetic materials, atomic layer deposition, ferromagnetic resonance, GIXRD, MFM, VSM, Brillouin light scattering, enhanced Gilbert damping

CNR authors

Fanciulli Marco, Longo Emanuele Maria, Mantovan Roberto, Belli Matteo, Cecchini Raimondo, Tallarida Graziella, Gubbiotti Gianluca, Longo Massimo, Wiemer Claudia

CNR institutes

IMM – Istituto per la microelettronica e microsistemi, IOM – Istituto officina dei materiali