Table 1. Pole field and gradient extracted from study.

	Magnetic field |B|			Field gradient ∂x|B|
	12 mA	30 mA	Saturation	12 mA	30 mA	Saturation
Experiment	0.51 T	0.87 T	—	17 MT m−1	28 MT m−1	—
Model	0.34 T	0.64 T	0.98 T	10 MT m−1	19 MT m−1	29 MT m−1

Values were measured at z=5 nm and are reported for drive currents of 12 mA (pole magnetization 0.83±0.07 T), 30 mA (1.57±0.08 T) and for magnetic saturation (2.4 T), respectively. The estimated error for the experimental values is +28%/−11% due to the uncertainty in the tip volume. The model values are probably slightly overestimated due to the few-nm thick protective layer of diamond-like carbon and Pt on top of the write pole. See Supplementary Material for details.