  Tunability of the partially ordered double perovskite (PODP) and coexisting
spin-glass phase in SrMn1-xWxO3 (x=0.20 to 0.40) have been studied using
neutron powder diffraction (NPD), muon spin relaxation (MuSR), and magnetic
susceptibility (X) measurements. Structural studies reveal that SrMn1-xWxO3
undergoes a quasi-continuous transformation from simple perovskite (Pm-3m) to
PODP (P21/n) phase as x increases. Xdc(T) and Xac(T) measurements show a sharp
cusp-like peak at a spin glass transition, Tg. The muon relaxation rate
({\lambda}) peaks at Tg following a critical growth, given by
{\lambda}={\lambda}(0).t-w [t=(T-Tg)/Tg]. However, no long-range magnetic order
is observed in NPD below Tg. These measurements confirm a tunable spin-glass
freezing in SrMn1-xWxO3 with Tg monotonously decreasing with W content, which
we attribute to tuning the relative concentration of the coexisting Mn-O-Mn and
Mn-O-W-O-Mn anti-ferromagnetic super-exchange pathways altering the geometric
frustration.
