Metal–insulator transitions
(MITs) in resistive
switching
materials can be triggered by an electric stimulus that produces significant
changes in the electrical response. When these phases have distinct
magnetic characteristics, dramatic changes in the spin excitations
are also expected. The transition metal oxide La
0.7
Sr
0.3
MnO
3
(LSMO) is a ferromagnetic metal at low temperatures
and a paramagnetic insulator above room temperature. When LSMO is
in its metallic phase, a critical electrical bias has been shown to
lead to an MIT that results in the formation of a paramagnetic resistive
barrier transverse to the applied electric field. Using spin-transfer
ferromagnetic resonance spectroscopy, we show that even for electrical
biases less than the critical value that triggers the MIT, there is
magnetic phase separation, with the spin-excitation resonances varying
systematically with applied bias. Therefore, voltage-triggered MITs
in LSMO can alter magnetic resonance characteristics, offering an
effective method for tuning synaptic weights in neuromorphic circuits.