ABSTRACT
Tunneling magnetoresistance (TMR) is a consequence of spin-dependent tunneling, and in a broader sense, is another manifestation of spin-dependent transport related to giant magnetoresistance (GMR) and anisotropic magnetoresistance (AMR) e¥ects. Spin-dependent tunneling between two ferromagnets, an outgrowth of earlier work by Meservey and Tedrow [1], was ¢rst proposed [2] and observed [3] in 1975 and was reliably demonstrated only in 1995 [4,5]. In the past decade, magnetic tunnel junctions (MTJs) have aroused considerable interest due to their suitability for applications in spin-electronic devices and indeed have found applications in hard disk read heads and magnetic random access memories (MRAMs). že diversity of the physical phenomena governing the operation of these magnetoresistive devices also makes MTJs very attractive from the fundamental physics point of view. žese facts have recently stimulated tremendous activity in both the experimental and theoretical realms of investigation, with a view to understanding and manipulating the electronic, magnetic, and transport properties of MTJs.
