US Patent 7745004 - Polymer coated magnetic particles

http://www.freepatentsonline.com/7745004.html

High frequency mobile communication devices often produce unnecessary radio emissions which deteriorate communication quality. Magnetic films having a nanogranular structure can be used as an EM shield to avoid this problem. This patent from Sony teaches a variation of magnetic nanomaterial in which manufacturing is lower cost and faster than previous methods. Claim 1 reads:

1. Magnetic particles forming a magnetic material for absorbing electromagnetic waves, wherein the magnetic particles have a diameter located within a range of 1 nm to 50 nm; and

a chain polymer surrounding individual ones of the magnetic particles being formed to a thickness of 1 nm or less.