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 doped with Mn in addition to the usual EPR signal of Mn2+. The non-resonant response increases with the increase of Mn2+ concentration in glasses. In contrast to the EPR signal, the magnitude of non-resonant absorption does not show saturation at high microwave power and grows much faster as the temperature decreases. The magneto-induced microwave conductivity in the glass dielectric is explained by the magnetic field-dependent electron tunneling between non-bridging oxygen ions adjacent to paramagnetic Mn2+ ions. The high probability of tunneling is provided by aligning the electron spins in Mn2+ and adjacent non-bridging oxygen ions in the external magnetic field.