  While it is commonly accepted that the disorder induced by magnetic ion
doping in quantum magnets usually generates a rugged free-energy landscape
resulting in slow or glassy spin dynamics, the disorder/distortion effects
associated with non-magnetic ion sites doping are still illusive. Here, using
AC susceptibility measurements, we show that the mixture of Sn/Ti on the
non-magnetic ion sites of pyrochlore $Yb_2(Ti_{1-x}Sn_x)_2O_7$ induces an
antiferromagnetic ground state despite both parent compounds, $Yb_2Ti_2O_7$,
and $Yb_2Sn_2O_7$, order ferromagnetically. Local structure studies through
neutron total scattering reveals the local distortion in the non-magnetic ion
sites and its strong correlation with the magnetic phase switching. Our study,
for the first time, demonstrates the local distortion as induced by the
non-magnetic ion site mixture could be a new path to achieve magnetic phase
switching, which has been traditionally obtained by external stimuli such as
temperature, magnetic field, pressure, strain, light, etc.
