Optically generated spin currents in Pt/magnetic insulator structures*

The generation and detection of pure spin current provides a pathway for solid-state devices to avoid Joule heating losses created in electric current architectures.  Despite the promise of loss-free, spin-based devices, integrating spin current technology into real-world applications has proven difficult.  Here, we use a Pt/YIG bilayer device to detect light from 390 to 2200 nm using the spin Seebeck effect.  We find that the nanometer-thick platinum layer is crucial for both spin current generation and detection.  Using a phase-sensitive, field-modulation technique, we determine the gradient across the YIG, ∇T, create by optical illumination, I, to be ∇T/I = 0.0975 °C·m/W.  This work reveals the possibility of using spin current generation and detection for broadband light detection devices.