Figure 2. Proximity-induced magnetization in TI/YIG at low temperatures.

(a) A typical anomalous Hall curve for a five QL (Bi_xSb_1−x)₂Te₃/YIG sample (x=0.24) at 13 K. The inset shows schematic illustration of Hall measurements. (b) Temperature dependence of the anomalous Hall resistance for the same sample, indicating that the mean surface-state proximity-induced exchange splitting drops below k_BT at ∼100 K. This temperature may be viewed as an effective critical temperature for proximity-induced surface-state magnetization. (c) 300 K VSM magnetic hysteresis loops for both in-plane and perpendicular magnetic fields. The inset shows a low-field in-plane hysteresis loop with a coercive field ∼2 Oe. (d) Schematic illustration of the SSE signal free from the proximity-induced anomalous Nernst effect. Below T_c, there is a spin-polarized TI interface layer, which may produce an anomalous Nernst signal mixed in the SSE signal. The spin-polarized TI layer does not exist above T_c.