Delocalized Electrons Mediated Magnetic Coupling in Mn Sn Codoped In2O3 Nanocrystals: Plasmonics Shows the Way

Abstract

Dilute magnetic semiconductor oxides (DMSO) are metal oxides doped with magnetic ions, where interaction between a delocalized charge carrier such as conduction band (CB) electron (e) and localized magnetic spin (for example, dopant Mn2+ ion) decides its potential as a future spintronic material.(1, 2) The possibility of manipulating this carrier–Mn2+ exchange coupling strength via quantum confinement of charge carriers in a semiconductor nanocrystal (NC) has already been reported.(3, 4) Gamelin et al. demonstrated CB e–Mn2+ ferromagnetic exchange interactions in Mn-doped ZnO NCs, where CB e was generated by photoexcitation in a strict anaerobic condition.(5) Here we introduce CB e in the air-stable ground state by Sn4+ doping in Mn–Sn codoped In2O3 NCs that exhibit CB e–Mn2+ ferromagnetic exchange interactions, yielding a nearly ideal (∼4.8 μB/Mn2+ ion) magnetic moment at 2 K and 70 kOe. Importantly, the plasmonic band of our NCs provides a way to distinguish delocalized CB e from defect-bound localized e, unlike electrical characterization that suffers from grain boundary related problems