Fig. 4: Exchange splitting.

a Splitting of the lowest energy peak for the YP device, on increasing B_Y, acquired at V_SD = –1.5 mV. A spin doublet is visible (gray lines), without exchange. b Dependence of the ground state and excited state transition potentials for DyP⁺/DyP on increasing B_z, acquired at V_SD = 1.5 mV. c Dependence of ground state and excited state transition potentials for DyP⁺/DyP on increasing B_x, acquired at V_SD = 1.5 mV. d Dependence of ground state and excited state transition potentials for DyP⁺/DyP on increasing B_y, acquired at V_SD = 1.5 mV. e Upper panel shows a separation of the magnetic levels vs. B_Y, for two DyP devices (triangles, full and open) and for the YP device (gray circles). Lines are fits to the data. Lower panel, expected evolution of the magnetic field levels for DyP⁺ (color) and YP⁺ (gray). Dy(III) spins are orange and porphyrin ones gray. All data were acquired at 20 mK.