Magneto-induced microwave conductivity in Mn2+-doped silicate glass

A non-resonant microwave absorption induced by low magnetic field (magneto- induced microwave conductivity) was observed in Na2O-CaO-MgO-SiO2 glasses d oped with Mn in addition to the usual EPR signal of Mn2+. The nonresonant r esponse increases with the increase of Mn2+ concentration in glasses. In co ntrast to the EPR signal, the magnitude of non-resonant absorption does not show saturation at high microwave power and grows much faster as the tempe rature decreases. The magneto-induced microwave conductivity in the glass d ielectric is explained by the magnetic field-dependent electron tunneling b etween non-bridging oxygen ions adjacent to paramagnetic Mn2+ ions. The hig h probability of tunneling is provided by aligning the electron spins in Mn 2+ and adjacent non-bridging oxygen ions in the external magnetic field. (C ) 2000 Elsevier Science B.V. All rights reserved.