Soumen Pradhan1,Oleg I. Lebedev2,Martando Rath2,Fabien Veillon2,Wilfrid Prellier2,M. S. Ramachandra Rao1
Indian Institute of Technology (IIT) Madras1,Laboratorie CRISMAT, Normandie Universite2
Soumen Pradhan1,Oleg I. Lebedev2,Martando Rath2,Fabien Veillon2,Wilfrid Prellier2,M. S. Ramachandra Rao1
Indian Institute of Technology (IIT) Madras1,Laboratorie CRISMAT, Normandie Universite2
In recent years, multiferroic systems have been the subject of enormous interest due to their wide range of applications in spintronics, sensors, actuators, multistate memory devices etc. Artificial superlattices (SLs) have gained much attention in current research because of their potential to realize new functionalities like ferroelectricity, multiferroicity and superconductivity. Here, we have explored magneto-capacitance (MC) performance in SLs of pure ferroelectric and ferromagnetic sublayers for multiferroic applications. K<b><sub>0</sub></b><b><sub>.</sub></b><b><sub>5</sub></b>Na<b><sub>0</sub></b><b><sub>.</sub></b><b><sub>5</sub></b>NbO<b><sub>3</sub></b> (KNN)/La<b><sub>0</sub></b><b><sub>.</sub></b><b><sub>67</sub></b>Sr<b><sub>0</sub></b><b><sub>.</sub></b><b><sub>33</sub></b>MnO<b><sub>3</sub></b> (LSMO) SLs with LSMO sublayer thicknesses of 5, 7, 9 and 11 unit cell (u.c.) keeping KNN thickness fixed at 6 u.c. were deposited on (001)-oriented SrTiO<b><sub>3</sub></b> substrates alternately for 15 times using pulsed laser deposition (PLD) technique. The crystallinity and layer-by-layer growth of both the constituents were confirmed from X-ray diffraction as well as transmission electron microscopy. SLs with LSMO layer of 9 and 11 u.c. show coherent growth on the substrates. The Curie temperature (T<b><sub>C</sub></b>) of <b>∼</b>206 K even in the SL with thicker LSMO sublayer indicates the presence of defects in the SLs. Also, spin-glass behavior in the SLs was observed below 50 K as confirmed from magnetic measurements. The insulating nature in the SLs with 7 and 9 u.c. and insulator to metal transition for 11 u.c. were observed in the transport study. However, defects induced large negative magneto-resistance (MR) of <b>∼</b>98% was realized at 100 K in the SLs with 9 and 11 u.c. The capacitance as well as magneto-capacitance show high value at low frequency and reduce monotonically upon increase in the frequency. This can be well explained by MR coupled Maxwell-Wagner relaxation model. Finally, the giant MC of <b>∼</b>766% at standard frequency of 1 kHz with 9 T magnetic field at 100 K for SL with optimum LSMO sublayer thickness of 9 u.c. can be used for multistate memory applications.