  The many body localization (MBL) of spin-1/2 fermions poses a challenging
problem. It is known that the disorder in the charge sector may be insufficient
to cause full MBL. Here, we study dynamics of a single hole in one dimensional
t-J model subject to a random magnetic field. We show that strong disorder that
couples only to the spin sector localizes both spin and charge degrees of
freedom. Charge localization is confirmed also for a finite concentration of
holes. While we cannot precisely pinpoint the threshold disorder, we conjecture
that there are two distinct transitions. Weaker disorder first causes
localization in the spin sector. Carriers become localized for somewhat
stronger disorder, when the spin localization length is of the order of a
single lattice spacing.
