Fig. 3: Simulations of the photo-thermoelectric response in mTBG.
From: Nano-imaging photoresponse in a moiré unit cell of minimally twisted bilayer graphene
a Profile of the electron temperature increase induced by local photoexcitation as a function of distance (x) from the excitation position (xtip), for a cooling length of 200 nm. b Calculated Seebeck coefficient as a function of position within two moiré unit cells separated by a domain wall at x = 0 nm. c Line trace of the calculated photovoltage across a domain wall using the thermal profile and Seebeck coefficient of a and b. d Illustration of the geometry used in our photocurrent simulations. The yellow semi-circles indicate contact probes, the green single-layer graphene regions and the orange mTBG regions. The red projection of current flows corresponds to a configuration wherein current flows between contacts 3 and 1, while the white field lines correspond to the current flowing between contacts 2 and 1. The black square highlights the region shown in e–g. e 2D spatial map of the calculated Seebeck coefficient (Supplementary Note 6) that goes into our model, along with the projections of current flows shown in d. f Zoom of the photovoltage simulations in the region of mTBG (same area as Fig. 2a). Here we convolute the calculated responsivity with a Gaussian function of width 15 nm to account for the finite tip radius. Colour code: blue: −1, red: +1. Length of scale bar: 500 nm. g Same as in f but for a different measurement geometry (same as Fig. 2b).
