A three terminal magnetic sensor (TTM) has a base region, a collector region which is adjacent the base region, an emitter region, and a barrier region which separates the emitter region from the base region. A sensing plane is defined along sides of the base region, the collector region, and the emitter region. An insulator layer is offset from the sensing plane and adjacent the collector region and the base region. A metal layer is offset from the sensing plane and in-plane and in contact with magnetic materials of the base region. This metal layer advantageously reduces an electrical resistance of the base region, which reduces signal noise in the TTM. Preferably, the metal layer has an electrical resistivity of less than 10 .mu..OMEGA.-centimeter (e.g. copper, gold, or ruthenium). The TTM may comprise a spin valve transistor (SVT), a magnetic tunnel transistor (MTT), or a double junction structure.