  We propose and demonstrate a new method to probe local spin polarization in
semiconductor micro devices at low and zero magnetic fields. By connecting a
single-lead quantum dot to a semiconductor micro device and monitoring electron
tunneling into singlet and triplet states in the dot, we can detect the local
spin polarization formed in the target device. We confirm the validity of this
detection scheme utilizing spin split quantum Hall edge states. We also observe
non-zero local spin polarization at the device edge in low magnetic fields,
which is not detectable with conventional macroscopic probes.
