Electrical control of magnetism has been demonstrated in multiferroic compounds and ferromagnetic semiconductors, but electrical switching of a substantial net magnetization at room temperature has not been demonstrated in these materials. This goal has instead been achieved in heterostructures comprising ferromagnetic films in which electrically driven magnetic changes arise due to strain or exchange bias from ferroic substrates, or due to charge effects induced by a gate. However, previous work focused on electrical switching of an in-plane magnetization or involved the assistance of applied magnetic fields.
In heterostructures made of juxtaposed ferroelectric and ferromagnetic layers, we have shown electrical control with no applied magnetic field of the perpendicular magnetization of small features  and of magnetic stripe domains patterns .
Here we investigate Ni81Fe19 films on ferroelectric substrates with and without buffer layers of Cu, whose presence precludes charge-mediated coupling. Ni81Fe19 has virtually zero magnetostriction, but sufficiently thin films show large magnetostriction, and thus, on increasing film thickness through the threshold for zero magnetostriction, we have seeked the crossover from charge- to strain-mediated coupling.
We will then show that strain associated with the motion of 90°- ferroelectric domain walls in a BaTiO3 substrate, can switch the magnetization of an array of overlying single-domain Ni dots.
 M. Ghidini, R. Pellicelli, J. L. Prieto, X. Moya, J. Soussi, J. Briscoe, S. Dunn and N. D. Mathur, Nature Communications 4 (2013) 1453.
 M. Ghidini, F.Maccherozzi, X. Moya, L. C. Phillips, W.Yan, J. Soussi, N. Métallier, M.Vickers, , N. -J.Steinke, R. Mansell, C. H. W. Barnes, S. S. Dhesi, and N. D. Mathur,
Adv. Mater.doi: 10.1002/adma.201404799 (2015).
Resistance fluctuations of low strain thin film La0.7Ca0.3MnO3 grown on NdGaO3 are examined. The appearance of two state resistance fluctuations are found to be correlated with the onset of remanent magnetization and not with the onset of percolation-like conduction. Their behavior with current, applied magnetic field, and temperature provide information on the nature of the fluctuation. In contrast to the magnetization at the putative Tc of the thin film, the resistance fluctuations display memory of the applied magnetic filed history. An explanation involving a strain enhanced AF interaction is posited.
Resistance fluctuations of low strain thin film La0.7Ca0.3MnO3grown on NdGaO3 show no dependence on low magnetic fields above Tc. At Tc, small volume local phase fluctuations are probed using the variance of the resistance noise power to give an upper bound fluctuator size scale of 100nm.
The resistance noise peak at Tc is seen to broaden with magnetic field. Below Tc, comparison of the thermodynamics with the transport effects of large two state resistance fluctuations indicate large current inhomogeneity. Their behavior is similar to local phase fluctuations seen on higher strain films. The sample resistance below Tc is shown not to be a unique function
of the bulk sample magnetization through a fluctuation-dissipation
argument. Evidence for low temperature aging in the resistance noise power is also presented.