Memory effect of magnetoelectric coupling in antiferromagnetic cobalt tantalate with honeycomb lattice.

• Memory effect of ME coupling in Co4Ta2O9 is revealed in the form of polarization memory effect: ME poling induced polarization below Néel temperature is recovered after Co4Ta2O9 is heated to paramagnetic nonpolar phase and then cooled to antiferromagnetic polar phase without being poled. • Polarization memory effect is attributed to polar nanoregions in paramagnetic phase due to short-range magnetic ordering as evidenced by heat capacity data deduced magnetic entropy. • If the applied magnetic field in paramagnetic phase is weakened, polarization memory effect is enhanced, which is ascribed to the less change of spin structure. If we switch the direction of this magnetic field, the polarization after reentering antiferromagnetic phase is also reversed. • ME coupling memory effect is also reflected in electric field dependent magnetization after the second cooling process without being poled. The two aspects of ME coupling are strongly correlated. Memory effect of magnetoelectric (ME) coupling is observed in antiferromagnetic Co 4 Ta 2 O 9 ME poling generated polarization below Néel temperature is retrieved after Co 4 Ta 2 O 9 is warmed to paramagnetic phase and then cooled to antiferromagnetic phase without being poled. This effect is ascribed to polar nanoregions in paramagnetic phase due to short range magnetic ordering as evidenced by temperature dependent magnetic entropy. If the applied magnetic field in paramagnetic phase is weakened, the memory effect is strengthened, which is ascribed to the less change of spin alignment induced by the weaker magnetic field. If we switch this magnetic field, the polarization when reentering polar phase is also reversed. Furthermore, the memory effect is also reflected in electric field dependent magnetization after the second cooling process without being poled. [ABSTRACT FROM AUTHOR]