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Epitaxial growth and characterization of the heusler alloy Mn3Ge for future use in magnetic tunnel junctions

Andreasson, Amanda LU (2019) PHYM01 20161
Solid State Physics
Department of Physics
Abstract
To allow further device scalability within the data storage industry there needs to be continued research of new technologies. One promising technology is the Magnetic Random Access Memory (MRAM), based on magnetoresistive elements, which is non-volatile; consume low power and have fast read and write operations. To make the technology scalable, the bit (the smallest element in the MRAM) needs to be stable of thermal fluctuations and switch efficiently. The bit is a Magnetic Tunnel Junction (MTJ) which is amongst one of the simplest spintronic devices. It consists of two ferromagnetic layers: one bottom layer with pinned magnetism and one top layer which is free and can switch its magnetic polarity. Between the two magnets, there is a... (More)
To allow further device scalability within the data storage industry there needs to be continued research of new technologies. One promising technology is the Magnetic Random Access Memory (MRAM), based on magnetoresistive elements, which is non-volatile; consume low power and have fast read and write operations. To make the technology scalable, the bit (the smallest element in the MRAM) needs to be stable of thermal fluctuations and switch efficiently. The bit is a Magnetic Tunnel Junction (MTJ) which is amongst one of the simplest spintronic devices. It consists of two ferromagnetic layers: one bottom layer with pinned magnetism and one top layer which is free and can switch its magnetic polarity. Between the two magnets, there is a tunnel barrier of 1-2 nm thickness where the majority and minority spin electrons can tunnel through. To enable future downscaling of the MTJ while improving storage capacity in MRAMs, one need to utilize ferromagnetic materials that are known for having perpendicular magnetic anisotropy and high spin polarization. One material with the mentioned properties is the tetragonal structure of D022-Mn3Ge, where D022 is a type of crystal structure and Mn3Ge is an alloy between Manganese and Germanium. Thin films were grown using molecular beam epitaxy which, when characterized, were found to have a high perpendicular magnetic anisotropy. One problem with the films were island formations due to a surface energy mismatch between the substrate and the thin film. The surface roughness needs further improvement as the surface must be atomically flat. Otherwise it would easily cause pinholes in the thin tunnel barrier. (Less)
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author
Andreasson, Amanda LU
supervisor
organization
course
PHYM01 20161
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8986244
date added to LUP
2019-06-20 10:52:37
date last changed
2019-06-20 10:52:37
@misc{8986244,
  abstract     = {{To allow further device scalability within the data storage industry there needs to be continued research of new technologies. One promising technology is the Magnetic Random Access Memory (MRAM), based on magnetoresistive elements, which is non-volatile; consume low power and have fast read and write operations. To make the technology scalable, the bit (the smallest element in the MRAM) needs to be stable of thermal fluctuations and switch efficiently. The bit is a Magnetic Tunnel Junction (MTJ) which is amongst one of the simplest spintronic devices. It consists of two ferromagnetic layers: one bottom layer with pinned magnetism and one top layer which is free and can switch its magnetic polarity. Between the two magnets, there is a tunnel barrier of 1-2 nm thickness where the majority and minority spin electrons can tunnel through. To enable future downscaling of the MTJ while improving storage capacity in MRAMs, one need to utilize ferromagnetic materials that are known for having perpendicular magnetic anisotropy and high spin polarization. One material with the mentioned properties is the tetragonal structure of D022-Mn3Ge, where D022 is a type of crystal structure and Mn3Ge is an alloy between Manganese and Germanium. Thin films were grown using molecular beam epitaxy which, when characterized, were found to have a high perpendicular magnetic anisotropy. One problem with the films were island formations due to a surface energy mismatch between the substrate and the thin film. The surface roughness needs further improvement as the surface must be atomically flat. Otherwise it would easily cause pinholes in the thin tunnel barrier.}},
  author       = {{Andreasson, Amanda}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Epitaxial growth and characterization of the heusler alloy Mn3Ge for future use in magnetic tunnel junctions}},
  year         = {{2019}},
}