Magnetic Nanostructures as Amplifiers of Transverse Fields in Magnetic Resonance

We introduce the concept of amplifying the transverse magnetic fields produced and/or detected with inductive coils in magnetic resonance settings by using the reversible transverse susceptibility properties of magnetic nanostructures. When a large magnetic field is applied perpendicular to the nanoparticle long axis, the particle becomes very sensitive to the perpendicular small AC field. This is advantageous for magnetic resonance detection, where one needs to amplify the signal in the presence of a large DC field. We have tested this property of nanoparticles up to 3MHz, and do not see (or expect) any variation up to frequencies of several giga-Hertz, which is beyond any reasonable nuclear magnetic resonance detection. transverse field amplification by magnetic nanoparticles provides not just an improvement in detection sensitivity, but also in magnetic resonance imaging resolution. Since the nanoparticle can in principle be only 5-10 nanometers in size, equivalent imaging spatial resolution would also be possible.