Magnetic properties of geometrically frustrated ZnxLi1−xV2O4

μSR spectroscopy on ZnV2O4 shows paramagnetism for T>40 K. For 12 K ⩽T⩽40 K , the paramagnetic state coexists with a dynamically correlated spin-glass-like state whose volume fraction increases as temperature is reduced, reaching 100% around 12 K. Cooling further leads to a highly damped Bessel-type oscillatory pattern which indicates an incommensurate spin-density-wave structure. The high transverse relaxation rate means large local spin disorder, probably preventing true long-range order, which would explain the absence of magnetic Bragg peaks in neutron diffraction. Furthermore, persistent slow spin fluctuations are observed. These features are indicators of frustration and it is concluded that the structural distortion around 50 K removes only some of the frustration. For Zn0.2Li0.8V2O4 no structural phase transition occurs and full frustration is expected. The μSR data show paramagnetic response above ∼12 K. The relaxation rate follows a critical law on approaching 12 K from above, as does the T1 relaxation in NMR. Below 12 K a fast relaxing dynamic Gaussian Kubo–Toyabe signal appears, which is the signature of a dynamic disordered magnetic state. Spin freezing is not observed down to 2 K. The formation of this dynamic spin-glass-like state is consistent with a spin-glass transition temperature of ∼10 K deduced from specific heat and magnetisation measurements.