Surface Engineered Enhanced Charge-to-Spin Conversion in Cd₃As₂ Thin Films

Cd₃As₂, a Dirac semimetal known for its topological properties where electrons behave as if they have no mass, hold immense promise for next-generation electronics. ^{[1, 2]} In this work, we investigate charge-to-spin conversion in epitaxial Cd₃As₂ thin films fabricated by molecular beam epitaxy (MBE) on suitable substrates. Charge-to-spin conversion was quantified using two complementary techniques: (i) spin-torque ferromagnetic resonance (ST-FMR), which measures microwave-driven spin currents in a heterostructure of Cd₃As₂ and ferromagnetic permalloy (Ni₈₀Fe₂₀), and (ii) DC non-local voltage measurements, detecting transverse voltages induced by spin accumulation in a bare Cd₃As₂ film. To tune the spin Hall angle and conversion efficiency in ST-FMR measurements, interfacial layers of Ag and MgO were engineered between Cd₃As₂ and permalloy, modulating spin-orbit coupling and interface transparency. Temperature-dependent measurements from cryogenic to room temperature revealed variations in conversion efficiency, correlating with the Lifshitz transition in Cd₃As₂—a topological phase change involving Fermi surface reconstruction around ~100 K. These findings demonstrate Cd₃As₂ as a promising platform for energy-efficient spintronic devices, such as SOT-MRAM, and highlight the role of interface engineering in optimizing topological spin phenomena. The work advances understanding of temperature-driven topological transitions, with implications for quantum computing and low-power electronics.

 

References:

1. Schumann, T., Goyal, M., Kim, H., & Stemmer, S. (2016). Molecular beam epitaxy of Cd3As2 on a III-V substrate. APL Materials, 4(12).

2. Schumann, T., Goyal, M., Kealhofer, D. A., & Stemmer, S. (2017). Negative magnetoresistance due to conductivity fluctuations in films of the topological semimetal C d 3 A s 2. Physical Review B, 95(24), 241113.