Magnetic hyperthermia in a system of dense cluster of ferromagnetic nanoparticles A.F. Abu-Bakr and A.Yu. Zubarev Eur. Phys. J. Special Topics, 229 2-3 (2020) 315-322 Published online: 11 February 2020 DOI: 10.1140/epjst/e2019-900096-y