Double loop hysteresis in direct current dependent dielectric permittivity of SrTiO3

Experimental double loop hysteresis in dc field dependent dielectric permittivity in bulk single crystal SrTiO3 is reported. Small signal measurements of the permittivity are performed in the frequency range 0.5–1.5 GHz at temperatures below 77 K using electrically thin circular parallel-plate resonators. The dielectric permittivity is extracted form the measured resonant frequency. The double loop hysteresis may be caused by field induced local paraelectric/ferroelectric phase transitions, and/or switching (polarization reversal) in local opposing ferroelectric domains associated with symmetry breaking impurities/structural defects.