New materials that have electronic functionality beyond that of simple semiconductors and metals are a fertile area of research. Complex oxides have been shown to exhibit colossal magnetoresistance effects, where the electrical resistance changes by orders of magnitude under a magnetic field. However the dynamics of charge transport in these compounds is still poorly understood. Recently, we have shown for the first time that colossal magnetoresistance can be found at terahertz frequencies. Importantly, we track the local motion of electrons using terahertz spectroscopy, and find that the effect is an intrinsic property of the conductive oxide. We gained insights into the relative length scales of electron motion, and how rapidly electrons scatter. Driving electronics at terahertz frequencies (10¹²Hz) is important for future devices and wireless communications.

Read more in our article in Nano Letters.

DOI: 10.1021/acs.nanolett.7b00231

Figure: Left - experimental geometry for oxide nanocomposites. Right - the conductivity at THz frequencies is strongly altered by a magnetic field.