**5**, 5100 (2014).

D. Wang, A. A. Bokov, Z.-G. Ye, J. Hlinka, and L. Bellaiche, Subterahertz dielectric relaxation in lead-free Ba(Zr,Ti)O$_{3}$ relaxor ferroelectrics. *Nat. Commun.* **7**, 11014 (2016).

D. Nuzhnyy, J. Petzelt, and M. Savinov, Broadband dielectric response of Ba(Zr,Ti)O$_{3}$ ceramics: from incipient via relaxor and diffuse up to classical ferroelectric behavior. *Phys. Rev. B* **86**, 1, (2012).

J. Petzelt, D. Nuzhnyy, M. Savinov, V. Bovtun, M. Kempa, T. Ostapchuk, J. Hlinka, G. Canu, and V. Buscaglia, Broadband dielectric spectroscopy of Ba(Zr,Ti)O$_{3}$: dynamics of relaxors and diffuse ferroelectrics.*Ferroelectrics* **469**, 14 (2014).

W. Kleemann, S. Miga, Z. K. Xu, S. G. Lu, and J. Dec, Non-linear permittivity study of the crossover from ferroelectric to relaxor and cluster glass in BaTi$_{1-x}$Sn$_{x}$O$_{3}$. *Appl. Phys. Lett.* **104**, 182910 (2014).

K. Uchino, Fractal Phenomena in Ferroelectrics. *J. Nanotech. Mater. Sci.* **1**, 1 (2014).

A. A. Bokov and Z.-G. Ye, Dielectric relaxation in relaxor ferroelectrics. *J. Adv. Dielectr.* **2**, 1241010 (2012).

A. Akbarzadeh, S. Prosandeev, E. Walter, A. Al-Barakaty, and L. Bellaiche, Finite-temperature properties of Ba(Zr, Ti)O$_{3}$ relaxors from first principles. *Phys. Rev. Lett.* **108**, 257601 (2012).

D. Sherrington, BZT: a soft pseudospin glass. *Phys. Rev. Lett.* **111**, 227601 (2013).

D. Sherrington, Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$: A minimal induced-moment 