  Many recipes for realizing topological superconductivity rely on broken
time-reversal symmetry, which is often attained by applying a substantial
external magnetic field. Alternatively, using magnetic materials can offer
advantages through low-field operation and design flexibility on the nanoscale.
Mechanisms for lifting spin degeneracy include exchange coupling,
spin-dependent scattering, spin injection-all requiring direct contact between
the bulk or induced superconductor and a magnetic material. Here, we implement
locally broken time-reversal symmetry through dipolar coupling from nearby
micromagnets to superconductor-semiconductor hybrid nanowire devices. Josephson
supercurrent is hysteretic due to micromangets switching. At or around zero
external magnetic field, we observe an extended presence of Andreev bound
states near zero voltage bias. We also show a zero-bias peak plateau of a
non-quantized value. Our findings largely reproduce earlier results where
similar effects were presented in the context of topological superconductivity
in a homogeneous wire, and attributed to more exotic time-reversal breaking
mechanisms [1]. In contrast, our stray field profiles are not designed to
create Majorana modes, and our data are compatible with a straightforward
interpretation in terms of trivial states in quantum dots. At the same time,
the use of micromagnets in hybrid superconductor-semiconductor devices shows
promise for future experiments on topological superconductivity.
