Fig. 4: Tunnelling characteristics of vertical Co/BN/BP devices.
From: Electric field-tunable ferromagnetism in a van der Waals semiconductor up to room temperature
a Left panel: Schematic drawing of the vertical Co/BN/BP MTJ devices studied in this work, which are grounded by a bottom-contacted graphene electrode. Right Panel: Schematic spin-resolved density of states of bulk Co (left) and of Co-BP (right) qualitatively reflects the DFT + U band structures. For Co-BP, the light-shaded red and blue areas represent the phosphorus p-derived bands, only slightly changed relative to pristine BP; the darker, peaked traces represent the narrow bands associated with the Co d orbitals. The energy ranges labelled I–IV refer to the corresponding device operation states discussed in the text. b Major (upper panel) and minor (lower panel) loop scans of the tunnelling magnetoresistance (TMR) of TMJ (Device C) under \({V}_{{{{\rm{g}}}}}=+ 20\) V at 2.5 K, with magnetic field parallel to the top Co electrode. c TMR of Device D at different gate voltages (\({V}_{{{{\rm{g}}}}}\)), measured at 2.5 K with \({I}_{{{{\rm{bias}}}}}=\) − 60 μA (DC) + 5 µA (AC). From top to bottom: Co-BP becomes increasingly p-type with the positive-to-negative \({V}_{{{{\rm{g}}}}}\) variation; background resistances are 1.5, 3.5, 7.6 and 2.7 kΩ, respectively (at \({B}_{{||}}=\) −60 mT). d TMR under Ibias= − 60 A (DC) + 5 µA (AC) in Device C at 300 K. Inset: The temperature dependence of TMR. The data are extracted from Supplementary Fig. S6.
