We demonstrate that spin-exchange dephasing of Larmor precession at near-earth-scale fields is effectively eliminated by dressing the alkali-metal atom spins in a sequence of AC-coupled 2-pi pulses, repeated at the Larmor precession frequency. The contribution of spin-exchange collisions to the spectroscopic line width is reduced by a factor of the duty cycle of the pulses. We experimentally demonstrate resonant transverse pumping in magnetic fields as high as 0.1 Gauss, present experimental measurements of the suppressed spin-exchange relaxation, and show enhanced magnetometer response relative to a light-narrowed scalar magnetometer.
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