A method of generating voltage and/or current oscillations in a single magnetic layer (200, 300), the magnetic layer having a thickness in a thickness direction, comprising: applying a direct voltage and/or current to the layer in a longitudinal direction perpendicular to the thickness direction; and developing a longitudinal voltage between a pair of longitudinal voltage leads (3 and 4 or 5 and 6) and/or a transverse voltage between a pair of transverse voltage leads (3 and 5 or 4 and 6); wherein the layer comprises a ferrimagnetic or antiferromagnetic material having a first and second magnetic sub-lattice, wherein the first sub-lattice is a dominant sub-lattice such that the charge carriers at the Fermi energy originate predominantly from the dominant sub-lattice and the charge carriers at the Fermi energy are spin polarised; and wherein: i) the first and second sub-lattices have an ordered non-collinear magnetic structure such that the angle between the local magnetic moment of the first and second sub-lattice is uniform in the layer and an azimuthal angle of the local magnetic moment of the first sub-lattice about the direction of the local magnetic moment of the second sub-lattice varies periodically along one or more spatial directions giving a magnetic texture, and the wavelength of the magnetic structure is longer than the Fermi wavelength; or ii) the first and second sub-lattice have a disordered non-collinear magnetic structure such that the angle between the local magnetic moment of the first and second sub-lattice is uniform in the layer and the azimuthal angle is non-uniform and/or random in the layer and the dominant current carrying sub-lattice lacks inversion symmetry; or iii) the first and second sub-lattices have a collinear magnetic structure at a current density below a first threshold current density and the dominant current carrying sub-lattice lacks inversion symmetry. the magnetic layer having a thickness in a thickness direction, comprising: applying a direct voltage and/or current to the layer in a longitudinal direction perpendicular to the thickness direction; and developing a longitudinal voltage between a pair of longitudinal voltage leads (3 and 4 or 5 and 6) and/or applying a direct voltage and/or current to the layer in a longitudinal direction perpendicular to the thickness direction; and developing a longitudinal voltage between a pair of longitudinal voltage leads (3 and 4 or 5 and 6) and/or a transverse voltage between a pair of transverse voltage leads (3 and 5 or 4 and 6); wherein the layer comprises a ferrimagnetic or antiferromagnetic material having a first and second magnetic sub-lattice, wherein the first sub-lattice is a dominant sub-lattice such that the charge carriers at the Fermi energy originate predominantly from the dominant sub-lattice and the charge carriers at the Fermi energy are spin polarised; and wherein: i) the first and second sub-lattices have an ordered non-collinear magnetic structure such that the angle between the local magnetic moment of the first and second sub-lattice is uniform in the layer and an azimuthal angle of the local magnetic moment of the first sub-lattice about the direction of the local magnetic moment of the second sub-lattice varies periodically along one or more spatial directions giving a magnetic texture, and the wavelength of the magnetic structure is longer than the Fermi wavelength; or ii) the first and second sub-lattice have a disordered non-collinear magnetic structure such that the angle between the local magnetic moment of the first and second sub-lattice is uniform in the layer and the azimuthal angle is non-uniform and/or random in the layer and the dominant current carrying sub-lattice lacks inversion symmetry; or iii) the first and second sub-lattices have a collinear magnetic structure at a current density below a first threshold current density and the dominant current carrying sub-lattice lacks inversion symmetry. i) the first and second sub-lattices have an ordered non-collinear magnetic structure such that the angle between the local magnetic moment of the first and second sub-lattice is uniform in the layer and an azimuthal angle of the local magnetic moment of the first sub-lattice about the direction of the local magnetic moment of the second sub-lattice varies periodically along one or more spatial directions giving a magnetic texture, and the wavelength of the magnetic structure is longer than the Fermi wavelength; or ii) the first and second sub-lattice have a disordered non-collinear magnetic structure such that the angle between the local magnetic moment of the first and second sub-lattice is uniform in the layer and the azimuthal angle is non-uniform and/or random in the layer and the dominant current carrying sub-lattice lacks inversion symmetry; or iii) the first and second sub-lattices have a collinear magnetic structure at a current density below a first threshold current density and the dominant current carrying sub-lattice lacks inversion symmetry.