Gapped and gapless short range ordered magnetic states with $(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ wavevectors in the pyrochlore magnet Tb$_{2+x}$Ti$_{2-x}$O$_{7+δ}$

E. Kermarrec, D. D. Maharaj, J. Gaudet +9