Fig. 1. Sample characterization. (a) TEM image of the single α-Fe₂O₃ nanowire. (b) HRTEM image and FFT ED pattern revealing single crystal structure of the nanowire. (c) XRD patterns and (d) Raman spectrum of the α-Fe₂O₃ nanowires.

Fig. 2. Suspended sample preparation. (a) SEM image of the grass-like grown α-Fe₂O₃ nanowire arrays on the Fe foil. (b) SEM image of some free lying individual α-Fe₂O₃ nanowires on the SiO₂/Si substrate. (c) Image of the micromanipulator miBot^TM armed with a sharp tungsten tip. (d) SEM image of the as-prepared suspended α-Fe₂O₃ nanowire whose two ends are fastened to the electrodes of the microdevice by EBID.

Fig. 3. (a) The schematic of the EBID process. (b) H vs. time shows the Pt/C deposition rate (20 nm/min). The red dash line is the best linear fitting to the data. (c) The typical cumulative thermal resistance (R_i) was obtained when the focused electron beam was scanning along the individual nanowires. The upper inset is the schematic of the electron beam self-heating technique and the lower shows the SEM image of the scanned nanowire. (d) Influence of EBID time/hight on the thermal contact of the nanowire shown in the lower inset of (c). The red balls and blue diamonds denote the thermal conductance and conductivity measured with the thermal bridge method at T = 300 K for the nanowire, respectively. The blue stars are the intrinsic thermal conductivity derived from the electron beam self-heating technique for the specific nanowire at T = 300 K. (e) The measured thermal resistance R (black diamonds) and the derived thermal contact resistance R_c (red balls) of the nanowire vs. time. (f) R_c/R vs. time. All the solid curves in (d)–(f) are a guide to the eyes.

Fig. 4. Temperature and size dependent thermal conductivity of the individual nanowires. (a) G vs. T. The red dash line shows the T⁻¹ dependency. (b) L/κ vs. d at T = 300 K, the green dashed line is a guide to the eyes.