Fig. 2: Ferroelectric capacitance of the OSH device 1.
From: Room temperature ferroelectricity in monolayer graphene sandwiched between hexagonal boron nitride
The four-probe resistance Rxx as functions of applied electric field (Vb/db) and magnetic field (B) during forward (a) and backward (b) sweeps of Vb. The inset illustrates the series-connected ferroelectric and geometric capacitances, i.e., Cf and Cg. n = Ctot (Vb - Vb0) and Cg = ϵϵ0/db, Vb0 is the Vb required to shift the Fermi level to the DP, ϵ0 is the permittivity of vacuum, and ϵ = 4 represents the relative permittivity. The extracted ferroelectric capacitances during forward (c) and backward (d) sweeps. Light gray-colored backgrounds highlight the negative capacitance regions. e The obtained polarization hysteresis loop. Arrows indicate the scanning directions of Vb/db. The inset sketches the mutual action of ferroelectric polarization PF and electric field E.
