Photovoltage detection of Damon-Eshbach and dipolar edge spin waves of nanomagnets with two-dimensional electron gas system

We report on a photovoltage technique that we use to probe spin excitations on submicron scales where surface effects play a dominant role. Localized spin wave modes were detected through the photovoltage induced in a two-dimensional electron gas (2DEG) system formed in a GaAs/ AlGaAs heterojunction. The two-dimensional nature of the detector separates the effects of the in-plane and normal vector components of magnetization. The high sensitivity of the technique arises from the low electron density and high electron mobility of 2DEGs relative to metals. The large magnetoresistance further introduces nonlinearity in the Hall coefficient that magnifies the photovoltage. Localized modes of spin waves confined in the magnetostatic potential of the demagnetizing field are observed. These determine the dynamic properties of the magnetization, which are relevant to high-density information storage.