EPR of Mn2+ in Fe(NH4)2(SO4)2

Abstract

X-band EPR measurements on ${\mathrm{Mn}}^{2+}$-doped single isostructural crystals of three Tutton salts M(${\mathrm{NH}}_{4}$${)}_{2}$(${\mathrm{SO}}_{4}$${)}_{2}$\ensuremath{\cdot}6H $_{2}\mathrm{O}$, M=Fe, Zn, and Mg, have been made at room, liquid-nitrogen, and liquid-helium temperatures. A least-squares fitting method, employing numerical diagonalization of the spin Hamiltonian matrix, fitting simultaneously a large number of resonant field line positions, has been adopted to accurately evaluate the spin Hamiltonian parameters. The intensities of lines at liquid-helium temperature have been used to determine the absolute signs of parameters. From the known shape of the paramagnetic sample (M=Fe), the ${\mathrm{Mn}}^{2+}$-${\mathrm{Fe}}^{2+}$ exchange interaction has been estimated to be 3.75 GHz in the paramagnetic host Fe(${\mathrm{NH}}_{4}$${)}_{2}$(${\mathrm{SO}}_{4}$${)}_{2}$\ensuremath{\cdot}6H $_{2}$O, using the g shift in the paramagnetic from that in the diamagnetic hosts (M=Zn, Mg).