A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer that is interposed between the first ferromagnetic layer and the second ferromagnetic layer. The tunnel barrier layer is a stacked body including one or more first oxide layers having a spinel structure and one or more second oxide layers having a spinel structure with a composition which is different from a composition of the first oxide layer.

A composition of matter consisting primarily of a stabilizing element and a transition metal oxide, wherein the transition metal oxide is an anti-ferromagnetic Mott insulator with strong spin orbit interactions, and the composition of matter has a canted crystal structure.

A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer that is interposed between the first ferromagnetic layer and the second ferromagnetic layer. The tunnel barrier layer is a stacked body including one or more first oxide layers having a spinel structure and one or more second oxide layers having a spinel structure with a composition which is different from a composition of the first oxide layer.

A magnetic material is constituted of a ferromagnetic or ferrimagnetic insulator in a double perovskite structure of Sr.sub.3-xA.sub.xOs.sub.1-yB.sub.yO.sub.6 (0.5≤x≤0.5, −0.5≤y≤0.5). A is an alkali metal or alkaline earth metal atom, and B is a transition metal atom, alkali metal atom, or alkaline earth metal atom). The insulator may be Sr.sub.3OsO.sub.6, where x=y=0 in the above formula. Sr.sub.3OsO.sub.6 is formed to have a cubic crystal structure where strontium atoms, osmium atoms, and oxygen atoms are arranged at lattice points.

A magnetic material is constituted of a ferromagnetic or ferrimagnetic insulator in a double perovskite structure of Sr.sub.3-xA.sub.xOs.sub.1-yB.sub.yO.sub.6 (0.5≤x≤0.5, −0.5≤y≤0.5). A is an alkali metal or alkaline earth metal atom, and B is a transition metal atom, alkali metal atom, or alkaline earth metal atom). The insulator may be Sr.sub.3OsO.sub.6, where x=y=0 in the above formula. Sr.sub.3OsO.sub.6 is formed to have a cubic crystal structure where strontium atoms, osmium atoms, and oxygen atoms are arranged at lattice points.

A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer that is interposed between the first ferromagnetic layer and the second ferromagnetic layer. The tunnel barrier layer is a stacked body including one or more first oxide layers having a spinel structure and one or more second oxide layers having a spinel structure with a composition which is different from a composition of the first oxide layer.

A magnetic material is constituted of a ferromagnetic or ferrimagnetic insulator in a double perovskite structure of Sr.sub.3-xA.sub.xOs.sub.1-yB.sub.yO.sub.6 (0.5x0.5, 0.5y0.5). A is an alkali metal or alkaline earth metal atom, and B is a transition metal atom, alkali metal atom, or alkaline earth metal atom). The insulator may be Sr.sub.3OsO.sub.6, where x=y=0 in the above formula. Sr.sub.3OsO.sub.6 is formed to have a cubic crystal structure where strontium atoms, osmium atoms, and oxygen atoms are arranged at lattice points.

A magnetic material is constituted of a ferromagnetic or ferrimagnetic insulator in a double perovskite structure of Sr.sub.3-xA.sub.xOs.sub.1-yB.sub.yO.sub.6 (0.5x0.5, 0.5y0.5). A is an alkali metal or alkaline earth metal atom, and B is a transition metal atom, alkali metal atom, or alkaline earth metal atom). The insulator may be Sr.sub.3OsO.sub.6, where x=y=0 in the above formula. Sr.sub.3OsO.sub.6 is formed to have a cubic crystal structure where strontium atoms, osmium atoms, and oxygen atoms are arranged at lattice points.

A magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer that is interposed between the first ferromagnetic layer and the second ferromagnetic layer. The tunnel barrier layer is a stacked body including one or more first oxide layers having a spinel structure and one or more second oxide layers having a spinel structure with a composition which is different from a composition of the first oxide layer.

Provided is an electromagnetic-wave absorber that can favorably absorb electromagnetic waves of a plurality of different frequencies in a high frequency band equal to or higher than the millimeter-wave band. The electromagnetic-wave absorber includes an electromagnetic-wave absorbing layer 1 in which a plurality of magnetic layers 1a-1e are stacked, each magnetic layer containing magnetic iron oxide that magnetically resonates at a high frequency in a band equal to or higher than the millimeter-wave band. A value of an anisotropic magnetic field (H.sub.A) of the magnetic iron oxide contained in at least one of the magnetic layers is different from that of the magnetic iron oxide contained in another of the magnetic layers.