Georgia Institute of Technology, School of PhysicsDoctoral thesis
Spin Transport in Aluminum Grains and Single Debye Relaxation in BST Nanoparticles
Georgia Institute of Technology, School of Physics · PhD dissertation, August 2007 (2007)
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Introduction
Zhang’s dissertation brings together two nanoparticle experiments. A Hanle measurement of aluminium grains in ferromagnetic tunnel junctions gave a spin-coherence time on the order of nanoseconds. In barium strontium titanate and barium titanate particles, the dielectric response showed a single Debye relaxation time with thermally activated behaviour below 200 K.
A closer reading
Both experiments extract a characteristic time from an electrical signal, but the times describe different physical processes. One tracks the loss of spin coherence and the other the response of electric polarization to an alternating field. Reading them together clarifies what each measurement can say about relaxation at similar length scales.