The disclosed technology relates generally to semiconductor devices, and more particularly to a layer stack for a magnetic tunnel junction (MTJ) device, and a method of forming the same. According to an aspect, a layer stack for a (MTJ) device comprises a seed layer structure, a pinning layer structure arranged above the seed layer structure, and above the pinning layer structure a Fe-comprising reference layer structure and a free layer structure separated by a tunnel barrier layer. The seed layer structure comprises a Ru-comprising layer and a Cr-comprising layer. The Cr-comprising layer forms an upper layer of the seed layer structure.

One illustrative MRAM cell disclosed herein includes a bottom electrode, a top electrode positioned above the bottom electrode and an MTJ (Magnetic Tunnel Junction) element positioned above the bottom electrode and below the top electrode. In this example, the MTJ element includes a bottom insulation layer positioned above the bottom electrode, a top insulation layer positioned above the bottom electrode; and a first ferromagnetic material layer positioned between the bottom insulation layer and the top insulation layer.

Some embodiments relate to a memory device. The memory device includes a magnetoresistive random-access memory (MRAM) cell comprising a magnetic tunnel junction (MTJ). The MTJ device comprises a stack of layers, comprising a bottom electrode disposed over a substrate. A seed layer disposed over the bottom electrode. A buffer layer is disposed between the bottom electrode and the seed layer. The buffer layer prevents diffusion of a diffusive species from the bottom electrode to the seed layer.

A magnetic sensing device includes a non-magnetic layer serving as a spacer and two magnetic layers that sandwich the spacer, and two oxide layers that sandwich the trilayer structure including the two magnetic layers and the spacer.

A spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device includes a substrate, a seed layer over the substrate, and a bismuth antimony (BiSb) layer having (0120) orientation on the seed layer. The seed layer includes a silicide layer and a surface control layer. The silicide layer includes a material of NiSi, NiFeSi, NiFeTaSi, NiCuSi, CoSi, CoFeSi, CoFeTaSi, CoCuSi, or combinations thereof. The surface control layer includes a material of NiFe, NiFeTa, NiTa, NiW, NiFeW, NiCu, NiCuM, NiFeCu, CoTa, CoFeTa, NiCoTa, Co, CoM, CoNiM, CoNi, NiSi, CoSi, NiCoSi, Cu, CuAgM, CuM, or combinations thereof, in which M is Fe, Cu, Co, Ta, Ag, Ni, Mn, Cr, V, Ti, or Si.

Provided are a magnetoresistive element, a magnetic memory device, and a writing and reading method for a magnetic memory device, in which an aspect ratio of a junction portion can be decreased. A magnetoresistive element 1 of the invention, includes: a heavy metal layer 2 that is an epitaxial layer; and a junction portion 3 including a recording layer 31 that is provided on the heavy metal layer 2 and includes a ferromagnetic layer of an epitaxial layer magnetized in an in-plane direction, which is an epitaxial layer, a barrier layer 32 that is provided on the recording layer 31 and includes an insulating body, and a reference layer 33 that is provided on the barrier layer 32 and has magnetization fixed in the in-plane direction, in which the recording layer 31 is subjected to magnetization reversal by applying a write current to the heavy metal layer 2.

A magnetic recording medium includes a substrate, a soft magnetic underlayer on the substrate, and a dual seed layer. The dual seed layer includes a first seed layer comprising NiFe at a first concentration, and a second seed layer comprising NiFe at a second concentration different from the first concentration and a segregant. The first seed layer may be on a soft magnetic underlayer and the second seed layer is on the first seed layer. The magnetic recording medium may further include one or more magnetic recording layers on the dual seed layer. The magnetic recording medium with the composition-graded dual seed layer may provide small grain size and good crystallographic texture for layers on the dual seed layer, including the magnetic recording layers.

Some embodiments relate to a memory device. The memory device includes a magnetoresistive random-access memory (MRAM) cell comprising a magnetic tunnel junction (MTJ). The MTJ device comprises a stack of layers, comprising a bottom electrode disposed over a substrate. A seed layer disposed over the bottom electrode. A buffer layer is disposed between the bottom electrode and the seed layer. The buffer layer prevents diffusion of a diffusive species from the bottom electrode to the seed layer.

A magneto-dielectric material operable between a minimum frequency and a maximum frequency, having: a plurality of layers that alternate between a dielectric material and a ferromagnetic material, lowermost and uppermost layers of the plurality of layers each being a dielectric material; each layer of the plurality of ferromagnetic material layers having a thickness equal to or greater than 1/15.sup.th a skin depth of the respective ferromagnetic material at the maximum frequency, and equal to or less than ⅕.sup.th the skin depth of the respective ferromagnetic material at the maximum frequency; each layer of the plurality of dielectric material layers having a thickness and a dielectric constant that provides a dielectric withstand voltage across the respective thickness of equal to or greater than 150 Volts peak and equal to or less than 1,500 Volts peak; and, the plurality of layers having an overall thickness equal to or less than one wavelength of the minimum frequency in the plurality of layers.

A magneto-dielectric material operable between a minimum frequency and a maximum frequency, having: a plurality of layers that alternate between a dielectric material and a ferromagnetic material, lowermost and uppermost layers of the plurality of layers each being a dielectric material; each layer of the plurality of ferromagnetic material layers having a thickness equal to or greater than 1/15.sup.th a skin depth of the respective ferromagnetic material at the maximum frequency, and equal to or less than ⅕.sup.th the skin depth of the respective ferromagnetic material at the maximum frequency; each layer of the plurality of dielectric material layers having a thickness and a dielectric constant that provides a dielectric withstand voltage across the respective thickness of equal to or greater than 150 Volts peak and equal to or less than 1,500 Volts peak; and, the plurality of layers having an overall thickness equal to or less than one wavelength of the minimum frequency in the plurality of layers.