Dynamic modulation of material properties by solid state proton gating

Abstract

As functionalities become more abundant in solid state devices, one key capability which remains lacking is an effective means to dynamically tune material properties. In this thesis, we establish a pathway towards this capability by utilizing the simplest ion known to mankind: the proton. We demonstrate for the first time dynamic control of magnetic properties in an all-solid-state heterostructures using solid state proton gating in a metal/oxide heterostructure. We also demonstrate dynamic modulation of magnetic anisotropy at a metal-metal interface through hydrogen insertion in a heavy metal adjacent to a ferromagnet. Besides magnetic properties, solid state proton gating also enables dynamic modulation of optical properties in a thin film oxide. We observe fast gating of optical reflectivity by ~10% at timescale down to ~20ms in a metal/oxide/metal heterostructure. Finally, we also demonstrate a room temperature reversible solid oxide fuel cell based on hydrogen storage. The cell has a small form factor which is suitable for energy storage in solid state microelectronics application. Our work hence provides a platform for complete control of material properties through solid state proton gating.