The development of low-noise, high-sensitivity magnetic sensors is essential for applications such as automotive systems, biomedical imaging, and magnetic microscopy. However, sensor performance has long been impeded by a fundamental constraint that noise and sensitivity increase concomitantly, which imposes a performance limit. Here, we show that this limit can be overcome by engineering spin-texture dynamics. While maintaining high sensitivity, the sensor noise is demonstrated to decrease inversely with enhanced spin-texture dynamics. Leveraging this mechanism, using synthetic ferrimagnets with accelerated spin-texture dynamics, low-noise and high-sensitivity anomalous-Hall sensors are constructed. With an active sensing area of $20\times 20{\mathrm{\mu m}}^2$, the device demonstrates a field detectability of $15.7\mathrm{nT}/\surd \mathrm{Hz}$ at 1 Hz, nearly an order of magnitude improvement over existing sensors based on ferromagnetic materials. Our results establish active control of spin textures as a general pathway to ultrasensitive, low-noise magnetic sensing platforms.

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• Spin texture
• Spintronics
• Ferrimagnets
• Magnetic multilayers