Figure 1: Structure of the organic spin valves and characterization of ferroelectricity in the epitaxial PZT.
From: Active control of magnetoresistance of organic spin valves using ferroelectricity
(a) Schematic structure of a Au/Co/Alq3/PZT/LSMO organic spin valve (FE-OSV). (b) Atomic force microscopy topography image of a PZT layer (5 nm in thickness) epitaxially grown on a LSMO (30 nm)/STO substrate. (c) PFM (phase) response measured after successively switching the polarization of the PZT film by applying +2.5 V and −2.5 V on the tip with respective to the LSMO bottom electrode. Note that the protocol of voltage polarity is different in PFM measurements from that in resistance measurements. (d) PFM image showing the polarization reversal by gradually increasing the applied voltage. The ‘up’ (‘down’) arrow corresponds to the polarization pointing out of (into) the film surface. Scale bar, 500 nm (b–d). (e) A typical polarization-voltage loop for the FE-OSV (device A). The black and pink circles illustrate the ‘minor loops’ corresponding to VMAX of ±0.5 and ±1.2 V, respectively. The orange (blue) arrow indicates the direction of the ramp voltage: sweeping down (up) before the MR scans. (f) TEM image for FE-OSV device. Different layers can be distinguished as labelled. Scale bar, 20 nm.
