Ferroelectric field effect modulation of the magnetic properties of colossal magnetoresistive La$_{1-x}$Sr$_x$MnO$_3$

In this work, we have tuned the magnetic properties of the colossal magnetoresistive oxide La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) using a ferroelectric field effect approach. Epitaxial LSMO thin films and ferroelectric Pb(Zr,Ti)O$_3$ (PZT) / LSMO heterostructures were fabricated using off-axis RF magnetron sputtering. LSMO films with high crystalline quality and atomically smooth surfaces have been achieved. Using the magneto-optical Kerr effect (MOKE), we measured a shift in the Curie temperature (T$_{\mathrm{c}}$) of LSMO upon switching the polarization direction of PZT, in agreement with the modulation of T$_{\mathrm{c}}$ found from magnetotransport measurements. Unlike the traditional chemical doping approach, the ferroelectric field effect approach allows one to control the magnetism in the system reversibly, without introducing additional lattice disorder/distortion.