The analysis of nanoparticle magnetization vibration using magnetic spectroscopy

The nanoparticle magnetization induced by a sinusoidal field is a distorted sinusoid and the amount of the distortion is determined by the mobility of the magnetizations. The distortion is higher for nanoparticle magnetizations with limited mobility. The mobility of the magnetizations is influenced by a variety of factors that are important in biomedical applications: temperature, viscosity and binding are perhaps the most obvious. The distortion can be quantified by a ratio of the Fourier coefficients, which is independent of concentration and can be measured in vivo. For example, we have introduced a method of measuring the temperature in vivo and the method can be extended to measure the other factors that influence the mobility of the magnetization.