講演情報
[11a-E214-4]Spin-alignment profile and electron transport mechanism in a polycrystalline ferrimagnetic NiCo2O4 film: A study based on the drastic current-induced change in resistivity-temperature characteristics
〇(M2)Shiho Sugiyama1, Masaaki Tanaka1,2,3, Ryosho Nakane1,3,4 (1.Tokyo Univ., 2.CSRN, Tokyo Univ., 3.NanoQuine, 4.d.lab)
キーワード：
magnetic oxide、spin-related transport、spin injection
NiCo2O4 (NCO), a theoretically half-metallic ferrimagnet, is a promising spin source for spintronic devices. Here, we investigate the spin-alignment profile of a polycrystalline NCO film on a Si substrate by analyzing current-induced changes in temperature-dependent resistivity (ρ–T). At 100 nA, the ρ–T curve shows semiconducting behavior over 4–290 K, consistent with hopping conduction dominated by spin-disordered, defect-rich regions near grain boundaries. With increasing current, a resistivity peak appears and shifts to higher temperature, reaching 162 K at 1 mA, while ρ at 290 K decreases to 0.7 mΩcm, comparable to that of high-quality epitaxial NCO films. We interpreted the observations using our spin-related transport framework. Spin-polarized conduction electrons are injected from nearly defect-free grain bodies into defect-rich near-grain-boundary regions, promoting spin alignment, reducing the hopping barrier, and increasing the Curie temperature there. These results reveal spatially different spin alignment in polycrystalline NCO and demonstrate current-induced control of the spin-alignment profile.