1 F NOISE IN ANISOTROPIC AND GIANT MAGNETORESISTIVE ELEMENTS/

Microfabricated magnetoresistive elements based on either the anisotro pic or the giant magnetoresistance effect were tested for their freque ncy dependent resistance noise behavior at room temperature in a de ma gnetic field, using a de sense current. Thermal resistance noise was t he dominant noise source above about 10 kHz, At low frequencies the re sistance noise was found to be dominated by a 1/f contribution that de pends on the applied magnetic field. The 1/f noise is relatively low a nd field independent when the element is in a saturated state and cont ains a relatively large and field dependent excess contribution when t he magnetic field is in the sensitive field range of the element. The 1/f noise level observed in saturation is comparable to the 1/f noise level found in nonmagnetic metals; the excess noise has a magnetic ori gin. The variation of the excess noise level with the applied de magne tic field can be explained qualitatively using a simple model based on thermal excitations of the magnetization direction, (C) 1997 American Institute of Physics.