Electrical\nControl of Magnetic Resonance in Phase\nChange Materials

Metal–insulator transitions\n(MITs) in resistive\nswitching\nmaterials can be triggered by an electric stimulus that produces significant\nchanges in the electrical response. When these phases have distinct\nmagnetic characteristics, dramatic changes in the spin excitations\nare also expected. The transition metal oxide La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> (LSMO) is a ferromagnetic metal at low temperatures\nand a paramagnetic insulator above room temperature. When LSMO is\nin its metallic phase, a critical electrical bias has been shown to\nlead to an MIT that results in the formation of a paramagnetic resistive\nbarrier transverse to the applied electric field. Using spin-transfer\nferromagnetic resonance spectroscopy, we show that even for electrical\nbiases less than the critical value that triggers the MIT, there is\nmagnetic phase separation, with the spin-excitation resonances varying\nsystematically with applied bias. Therefore, voltage-triggered MITs\nin LSMO can alter magnetic resonance characteristics, offering an\neffective method for tuning synaptic weights in neuromorphic circuits.