Gauge fields are ubiquitous in modern quantum physics. In superfluids, quantized vortices can be induced by gauge fields. Here we demonstrate the first experimental observation of vortex nucleations in light-dressed spinor Bose-Einstein condensates under radially localized synthetic magnetic fields. The light-induced spin-orbital-angular-momentum coupling creates azimuthal gauge potentials $\overrightarrow{A}$ for the lowest-energy spinor branch dressed eigenstate. The observation of the atomic wave function in the lowest-energy dressed eigenstate reveals that vortices nucleate from the cloud center of a vortex-free state with canonical momentum $\overrightarrow{p}=0$. This is because a large circulating azimuthal velocity field $\propto \overrightarrow{p}-\overrightarrow{A}$ at the condensate center results in a dynamically unstable localized excitation that initiates vortex nucleations. Furthermore, the long-time dynamics to reach the ground state stops in a metastable state when $|\overrightarrow{A}|$ is not sufficiently large. Our observation has reasonable agreement with the time-dependent Gross-Pitaevskii simulations.

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• Bose-Einstein condensates
• Spin-orbit coupling
• Synthetic gauge fields