Devices are described that include a multi-layered structure that is non-magnetic at room temperature, and which comprises alternating layers of Co and at least one other element E (such as Ga, Ge, and Sn). The composition of this structure is represented by Co.sub.1-xE.sub.x, with x being in the range from 0.45 to 0.55. The structure is in contact with a first magnetic layer that includes a Heusler compound. An MRAM element may be formed by overlying, in turn, the first magnetic layer with a tunnel barrier, and the tunnel barrier with a second magnetic layer (whose magnetic moment is switchable). Improved performance of the MRAM element may be obtained by placing a pinning layer between the first magnetic layer and the tunnel barrier.

The present invention relates to a spin torque oscillator with high power output and its applications. A spin torque oscillator may include a first magnetic reference layer having a fixed magnetization, a magnetic precession layer having a magnetization capable of precessing about an initial direction, and a first barrier layer interposed between the first magnetic reference layer and the magnetic precession layer. The first barrier layer is formed of an insulating material capable of inducing a negative differential resistance for the spin torque oscillator.

This semiconductor device comprises an active layer that is formed of an oxide magnetic material and a porous dielectric body that contains water and is provided on the active layer. By using hydrogen ions and hydroxide ions which are formed by electrolysis of water, the crystal structure of the active layer is changed between a ferromagnetic metal and an antiferromagnetic insulating body.

A structure includes an electronically controllable ferromagnetic oxide structure that includes at least three layers. The first layer comprises STO. The second layer has a thickness of at least about 3 unit cells, said thickness being in a direction substantially perpendicular to the interface between the first and second layers. The third layer is in contact with either the first layer or the second layer or both, and is capable of altering the charge carrier density at the interface between the first layer and the second. layer. The interface between the first and second layers is capable of exhibiting electronically controlled ferromagnetism.

A magnetoresistance effect element has a first ferromagnetic metal layer, a second ferromagnetic metal layer, and a tunnel barrier layer that is sandwiched between the first and second ferromagnetic metal layers, the tunnel barrier layer is expressed by a chemical formula of AB.sub.2O.sub.x, and has a spinel structure in which cations are arranged in a disordered manner, A represents a divalent cation that is either Mg or Zn, and B represents a trivalent cation that includes a plurality of elements selected from the group consisting of Al, Ga, and In.

A magnetoresistance effect element has a first ferromagnetic metal layer, a second ferromagnetic metal layer, and a tunnel barrier layer that is sandwiched between the first and second ferromagnetic metal layers, and the tunnel barrier layer has a spinel structure represented by a composition formula AGa.sub.2O.sub.x (0<x4), and an A-site is a non-magnetic divalent cation which is one or more selected from a group consisting of magnesium, zinc and cadmium.

The present invention relates to a spin torque oscillator with high power output and its applications. A spin torque oscillator may include a first magnetic reference layer having a fixed magnetization, a magnetic precession layer having a magnetization capable of precessing about an initial direction, and a first barrier layer interposed between the first magnetic reference layer and the magnetic precession layer. The first barrier layer is formed of an insulating material capable of inducing a negative differential resistance for the spin torque oscillator.

A magnetoresistance effect element has a first ferromagnetic metal layer, a second ferromagnetic metal layer, and a tunnel barrier layer that is sandwiched between the first and second ferromagnetic metal layers, the tunnel barrier layer is expressed by a chemical formula of AB.sub.2O.sub.x, and has a spinel structure in which cations are arranged in a disordered manner, A represents a divalent cation that is either Mg or Zn, and B represents a trivalent cation that includes a plurality of elements selected from the group consisting of Al, Ga, and In.

A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer positioned between the first ferromagnetic layer and the second ferromagnetic layer, and at least one of the first ferromagnetic layer and the second ferromagnetic layer is a Heusler alloy represented by the following General Formula (1):
Co.sub.2Fe.sub.X.sub.(1)
(in Formula (1), X represents one or more elements selected from the group consisting of Mn, Cr, Si, Al, Ga and Ge, and and represent numbers that satisfy 2.3+, <, and 0.5<1.9).

According to one embodiment, a memory device includes a stacked body and a controller. The stacked body includes a first magnetic layer, a second magnetic layer stacked with the first magnetic layer, and a first nonmagnetic layer provided between the first magnetic layer and the second ferromagnetic layer. The second ferromagnetic layer includes a first portion and a second portion stacked with the first portion. The controller causes a current to flow in the stacked body in a programming period. The programming period includes a first and a second period. The current has a first value in the first period and a second value in the second period. The second value is less than the first value.