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MLC and SThM schematic. Each MLC terminal is connected to 100 Ni electrodes, but we only show three for clarity. Voltage V was applied to the MLC terminals via thin copper wires of diameter ∼0.12 mm. The SThM tip resistance R t dominates the series lead and contact resistances, and forms one arm of a Wheatstone bridge. Prior to measurement of V out, the bridge was balanced using variable resistor R 3.
SThM measurements of EC effects in an MLC. (a) Temperature change ΔT versus time, on applying and removing V = 200 V as indicated. (b) EC heating (open circles) and cooling (closed circles) as a function of tip-sample separation. Data for MLC#1.
EC effects in an MLC measured by IRI with black-body calibration. (a) Initial 850 μm × 500 μm image showing part of the nominally isothermal MLC terminal. Emissivity variations due to surface roughness yield fictitious spatial variations in temperature. (b) On applying and removing V = 200 V at the times indicated, the ∼50 μm-diameter regions numbered 1-4 in (a) show average EC temperature changes that are similar to the accurately measured changes presented in Fig. 4 . Data for MLC#1.
EC effects in an MLC measured by IRI with accurate calibration. Average temperature change ΔT versus time for a ∼50 μm-diameter region of the nominally isothermal MLC terminal, on applying and removing V = 200 V as indicated. Data for MLC#1.
EC effects in an MLC measured by IRI. The 200 μm × 400 μm images show temperature variations in a corner of the MLC terminal due to the application (top half of figure) and subsequent removal (bottom half of figure) of 200 V. Emissivity variations due to surface roughness yield fictitious spatial variations in temperature. The colour scale renders the largest EC changes in photon flux equivalent to the 0.50 K changes observed in Fig. 4 . The average temperature change ΔT in a 50 μm-diameter region (circled) is plotted as a function of time. In these plots, the temperature is scaled to match the 0.50 K changes observed in Fig. 4 , and black lines show the time at which each image was obtained. Data for MLC#2, which is equivalent to MLC#1.
Schematic (not to scale) showing 150 μm-wide Pt track (black) on Si substrate (white), for SThM study of Joule heating. Heating in the 2 mm-diameter circular contact pads is negligible.
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