Alfred Cerezo | University of Oxford (original) (raw)

Papers by Alfred Cerezo

Research paper thumbnail of Position-Sensitive Atom Probe Analysis of Multi-Quantum Well Structures

Le Journal de Physique Colloques, 1989

Research paper thumbnail of 36th International Field Symposium, July 31, August 4, 1989, Oxford, Great-Britain

Research paper thumbnail of Microstructure and domain studies in Alnico 5 and Alnico 7 (abstract)

Journal of Applied Physics, 1985

Magnetization processes in Alnico alloys depend on details of the microstructure on a very fine s... more Magnetization processes in Alnico alloys depend on details of the microstructure on a very fine scale. In this paper, we report the results of studies carried out in more detail and at higher resolution than any previous study. Field ion microscopy (FIM) and atom probe microanalysis (AP) were used for microstructure studies, and high-voltage electron microscopy (HVEM) for studies of

Research paper thumbnail of Atom probe field–ion microscopy characterisation of ultra–fine structures in maraging steels

Research paper thumbnail of Thermal stability of electrodeposited nanocrystalline Co-1.1at.%P

Research paper thumbnail of Oxidation of Thin Al Layers for Magnetic Tunnel Barriers: a Three-dimensional Atom Probe Study

Microscopy and Microanalysis, 2006

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois,... more Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Research paper thumbnail of Partitioning behavior of Al in a nanocrystalline FeZrBAl soft magnetic alloy

Journal of Applied Physics, 2000

ABSTRACT The nanocrystalline Fe-Si-B-Nb-Cu alloy, known as FINEMET, is now a well established com... more ABSTRACT The nanocrystalline Fe-Si-B-Nb-Cu alloy, known as FINEMET, is now a well established commercial soft magnetic material exhibiting excellent permeability while maintaining a high saturation magnetization. It is produced by melt-spinning to form a ribbon with an amorphous structure. The purpose of this investigation was to use 3-dimensional atom probe microanalysis to experimentally quantify the local phase chemistries of this nanocomposite microstructure, with particular reference to the partitioning behavior of the Al.

Research paper thumbnail of Fabrication and characterization - by High Resolution Electron Microscopy and atom probe microanalysis - of Co-based metallic multilayer films

Proceedings, annual meeting, Electron Microscopy Society of America, 1990

The fabrication of multilayer films (MLF) with layer thicknesses down to one monolayer has led to... more The fabrication of multilayer films (MLF) with layer thicknesses down to one monolayer has led to the development of materials with unique properties not found in bulk materials. The properties of interest depend critically on the structure and composition of the films, with the interfacial regions between the layers being of particular importance. There are a number of magnetic MLF systems based on Co, several of which have potential applications as perpendicular magnetic (e.g Co/Cr) or magneto-optic (e.g. Co/Pt) recording media. Of particular concern are the effects of parameters such as crystallographic texture and interface roughness, which are determined by the fabrication conditions, on magnetic properties and structure.In this study we have fabricated Co-based MLF by UHV thermal evaporation in the prechamber of an atom probe field-ion microscope (AP). The multilayers were deposited simultaneously onto cobalt field-ion specimens (for AP and position-sensitive atom probe (POSAP...

Research paper thumbnail of Characterisation of multilayer materials using a position-sensitive atom probe

Proceedings, annual meeting, Electron Microscopy Society of America, 1990

The position sensitive atom probe (POSAP), described briefly elsewhere in these proceedings, perm... more The position sensitive atom probe (POSAP), described briefly elsewhere in these proceedings, permits both chemical and spatial information in three dimensions to be recorded from a small volume of material. This technique is particularly applicable to situations where there are fine scale variations in composition present in the material under investigation. We report the application of the POSAP to the characterisation of semiconductor multiple quantum wells and metallic multilayers.The application of devices prepared from quantum well materials depends on the ability to accurately control both the quantum well composition and the quality of the interfaces between the well and barrier layers. A series of metal organic chemical vapour deposition (MOCVD) grown GaInAs-InP quantum wells were examined after being prepared under three different growth conditions. These samples were observed using the POSAP in order to study both the composition of the wells and the interface morphology. ...

Research paper thumbnail of Atom Probe Studies of Interfaces in Metallic Multilayers

MRS Proceedings, 1991

The atom probe field-ion microscope has been used to study the diffusion at interfaces in metalli... more The atom probe field-ion microscope has been used to study the diffusion at interfaces in metallic multilayers deposited directly onto field-ion specimens and to develop models for the solid state reactions occuring at the atomic-scale in multilayer systems. Results are presented for the low temperature annealing of a Co-Ni multilayer. Intermixing over about 2 atomic planes is found even in as-deposited samples, extending to mnm after heating at 300°C for 1 hour. Using atom probe results from bulk alloys, a Monte Carlo simulation has been developed for the Fe-Cr system, in which a miscibility gap exists, and is being used in an attempt to model the behaviour of interfaces in Fe-Cr multilayers. Preliminary results are presented, showing that interfaces which are initially mixed over 10 atomic planes become sharper by an ‘interface spinodal’ reaction.

Research paper thumbnail of The effect of laser pulse shape on mass resolution in the pulsed-laser atom probe

Journal of Physics E: Scientific Instruments, 1987

ABSTRACT

Research paper thumbnail of Observations on the Microstructure and Magnetization of Alnico Permanent Magnets

Le Journal de Physique Colloques, 1984

Research paper thumbnail of Three dimensional atom probe and field ion microscopy analysis of Co/Pd multilayers for perpendicular media applications

Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401)

ABSTRACT Perpendicular magnetic recording is being considered as an important candidate for achie... more ABSTRACT Perpendicular magnetic recording is being considered as an important candidate for achieving extremely high density magnetic recording with high thermal stability. One set of materials being most widely studied for this application are Co/Pd and Co/Pt multilayer films. A series of Co/Pd multilayer films, seeded with a Ti-based bilayer seed, were deposited on Si wafers that had been patterned into posts of about 3 micron diameter. Following deposition the posts were patterned using a focus ion beam (FIB) system to form the needle-shaped samples required for 3DAP analysis. The atomic scale composition distribution was characterised using 3DAP, and HREM was used to characterise the atomic scale structure of the films.

Research paper thumbnail of The application of three-dimensional atom probe analysis to GMR materials

Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401)

ABSTRACT We discuss the giant magnetoresistance (GMR) property of CoFe/Cu magnetic multilayers. T... more ABSTRACT We discuss the giant magnetoresistance (GMR) property of CoFe/Cu magnetic multilayers. TEM images of the Co/Pt multilayer film show the crystal structure in the layers.

Research paper thumbnail of Smoother Shank Profile for Atom Probe Specimens Prepared by the Multi-step Focused Ion Beam Milling

2006 19th International Vacuum Nanoelectronics Conference, 2006

Focused ion beam (FIB) milling has been successfully used to prepare a range of atom probe specim... more Focused ion beam (FIB) milling has been successfully used to prepare a range of atom probe specimens from metal alloys at site specific locations such as grain boundaries, thin ribbons, powders, and multilayer film materials. Commonly employed, 3-step process generates ledges that act as a stress concentration sites at the shank of the specimens. Smoother shank profile of the specimen is therefore desirable, so as to reduce the chance of specimen failure at such points. In this work, an improved method to fabricate the specimens from planar multilayer thin films was presented. The films were deposited onto etched Si posts, prepared by the lithographic patterning of a Si wafer. Capping layers (e.g. Cu, Ni, and Fe) were deposited on top to protect the films of interest from implantation damage caused by the high energy ion beams. Individual posts were attached to the tip of sharpened metal wires, and subsequently sharpened by ion milling in a FEI FIB 200 instrument without further Pt deposition required

Research paper thumbnail of Atomic Scale Study Of Precipitate / Matrix Interfaces in a Metallic Alloy

MRS Proceedings, 1997

ABSTRACTThe study of phase transformations involves making assumptions about interfaces within a ... more ABSTRACTThe study of phase transformations involves making assumptions about interfaces within a material in order to apply mathematical models. An example of this is the Gibbs classical theory of nucleation and growth which is based upon the assumption that the precipitate / matrix interface is sharp. Recent developments in atom probe microscopy have made it possible for the first time to characterize complex three-dimensional internal interfaces within materials to sub-nanometre accuracy. We have used the OPoSAP (Optical Position Sensitive Atom Probe) to characterize the precipitate / matrix interface in the dilute Cu-Co system which is a model alloy for the study of homogeneous nucleation and growth. Interface widths derived from radial composition profiles were measured to be 0.9 ± 0.2 nm in size. The effects of thermal energy, positioning inaccuracies, and statistical limitations on the measurement of interface widths are examined through the use of mathematical models and comp...

Research paper thumbnail of Summary of Discussion at the 1ST Workshop on 3-DIMENSIONAL Atom-Probe Analysis-Its Present and Future

Research paper thumbnail of Characterization of Segregation and Precipitation at Grain Boundaries in Thermally Aged Pressure Vessel Steels

2006 19th International Vacuum Nanoelectronics Conference, 2006

... Vessel Steels G. Shal*, S. Hirosawa2, A. MorleyI, A. Cerezol, GDW Smith', D. Ellis3 and ... more ... Vessel Steels G. Shal*, S. Hirosawa2, A. MorleyI, A. Cerezol, GDW Smith', D. Ellis3 and T Williams3 2 ... DE21 7XX * Corresponding author: tel: +44 1865 273711, fax: +44 1865 273789, e-mail:gang.sha@materials.ox.ac.uk. Grain ...

Research paper thumbnail of Numerical modelling of mass resolution in a scanning atom probe

Research paper thumbnail of Einzel lenses in atom probe designs

Research paper thumbnail of Position-Sensitive Atom Probe Analysis of Multi-Quantum Well Structures

Le Journal de Physique Colloques, 1989

Research paper thumbnail of 36th International Field Symposium, July 31, August 4, 1989, Oxford, Great-Britain

Research paper thumbnail of Microstructure and domain studies in Alnico 5 and Alnico 7 (abstract)

Journal of Applied Physics, 1985

Magnetization processes in Alnico alloys depend on details of the microstructure on a very fine s... more Magnetization processes in Alnico alloys depend on details of the microstructure on a very fine scale. In this paper, we report the results of studies carried out in more detail and at higher resolution than any previous study. Field ion microscopy (FIM) and atom probe microanalysis (AP) were used for microstructure studies, and high-voltage electron microscopy (HVEM) for studies of

Research paper thumbnail of Atom probe field–ion microscopy characterisation of ultra–fine structures in maraging steels

Research paper thumbnail of Thermal stability of electrodeposited nanocrystalline Co-1.1at.%P

Research paper thumbnail of Oxidation of Thin Al Layers for Magnetic Tunnel Barriers: a Three-dimensional Atom Probe Study

Microscopy and Microanalysis, 2006

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois,... more Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Research paper thumbnail of Partitioning behavior of Al in a nanocrystalline FeZrBAl soft magnetic alloy

Journal of Applied Physics, 2000

ABSTRACT The nanocrystalline Fe-Si-B-Nb-Cu alloy, known as FINEMET, is now a well established com... more ABSTRACT The nanocrystalline Fe-Si-B-Nb-Cu alloy, known as FINEMET, is now a well established commercial soft magnetic material exhibiting excellent permeability while maintaining a high saturation magnetization. It is produced by melt-spinning to form a ribbon with an amorphous structure. The purpose of this investigation was to use 3-dimensional atom probe microanalysis to experimentally quantify the local phase chemistries of this nanocomposite microstructure, with particular reference to the partitioning behavior of the Al.

Research paper thumbnail of Fabrication and characterization - by High Resolution Electron Microscopy and atom probe microanalysis - of Co-based metallic multilayer films

Proceedings, annual meeting, Electron Microscopy Society of America, 1990

The fabrication of multilayer films (MLF) with layer thicknesses down to one monolayer has led to... more The fabrication of multilayer films (MLF) with layer thicknesses down to one monolayer has led to the development of materials with unique properties not found in bulk materials. The properties of interest depend critically on the structure and composition of the films, with the interfacial regions between the layers being of particular importance. There are a number of magnetic MLF systems based on Co, several of which have potential applications as perpendicular magnetic (e.g Co/Cr) or magneto-optic (e.g. Co/Pt) recording media. Of particular concern are the effects of parameters such as crystallographic texture and interface roughness, which are determined by the fabrication conditions, on magnetic properties and structure.In this study we have fabricated Co-based MLF by UHV thermal evaporation in the prechamber of an atom probe field-ion microscope (AP). The multilayers were deposited simultaneously onto cobalt field-ion specimens (for AP and position-sensitive atom probe (POSAP...

Research paper thumbnail of Characterisation of multilayer materials using a position-sensitive atom probe

Proceedings, annual meeting, Electron Microscopy Society of America, 1990

The position sensitive atom probe (POSAP), described briefly elsewhere in these proceedings, perm... more The position sensitive atom probe (POSAP), described briefly elsewhere in these proceedings, permits both chemical and spatial information in three dimensions to be recorded from a small volume of material. This technique is particularly applicable to situations where there are fine scale variations in composition present in the material under investigation. We report the application of the POSAP to the characterisation of semiconductor multiple quantum wells and metallic multilayers.The application of devices prepared from quantum well materials depends on the ability to accurately control both the quantum well composition and the quality of the interfaces between the well and barrier layers. A series of metal organic chemical vapour deposition (MOCVD) grown GaInAs-InP quantum wells were examined after being prepared under three different growth conditions. These samples were observed using the POSAP in order to study both the composition of the wells and the interface morphology. ...

Research paper thumbnail of Atom Probe Studies of Interfaces in Metallic Multilayers

MRS Proceedings, 1991

The atom probe field-ion microscope has been used to study the diffusion at interfaces in metalli... more The atom probe field-ion microscope has been used to study the diffusion at interfaces in metallic multilayers deposited directly onto field-ion specimens and to develop models for the solid state reactions occuring at the atomic-scale in multilayer systems. Results are presented for the low temperature annealing of a Co-Ni multilayer. Intermixing over about 2 atomic planes is found even in as-deposited samples, extending to mnm after heating at 300°C for 1 hour. Using atom probe results from bulk alloys, a Monte Carlo simulation has been developed for the Fe-Cr system, in which a miscibility gap exists, and is being used in an attempt to model the behaviour of interfaces in Fe-Cr multilayers. Preliminary results are presented, showing that interfaces which are initially mixed over 10 atomic planes become sharper by an ‘interface spinodal’ reaction.

Research paper thumbnail of The effect of laser pulse shape on mass resolution in the pulsed-laser atom probe

Journal of Physics E: Scientific Instruments, 1987

ABSTRACT

Research paper thumbnail of Observations on the Microstructure and Magnetization of Alnico Permanent Magnets

Le Journal de Physique Colloques, 1984

Research paper thumbnail of Three dimensional atom probe and field ion microscopy analysis of Co/Pd multilayers for perpendicular media applications

Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401)

ABSTRACT Perpendicular magnetic recording is being considered as an important candidate for achie... more ABSTRACT Perpendicular magnetic recording is being considered as an important candidate for achieving extremely high density magnetic recording with high thermal stability. One set of materials being most widely studied for this application are Co/Pd and Co/Pt multilayer films. A series of Co/Pd multilayer films, seeded with a Ti-based bilayer seed, were deposited on Si wafers that had been patterned into posts of about 3 micron diameter. Following deposition the posts were patterned using a focus ion beam (FIB) system to form the needle-shaped samples required for 3DAP analysis. The atomic scale composition distribution was characterised using 3DAP, and HREM was used to characterise the atomic scale structure of the films.

Research paper thumbnail of The application of three-dimensional atom probe analysis to GMR materials

Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401)

ABSTRACT We discuss the giant magnetoresistance (GMR) property of CoFe/Cu magnetic multilayers. T... more ABSTRACT We discuss the giant magnetoresistance (GMR) property of CoFe/Cu magnetic multilayers. TEM images of the Co/Pt multilayer film show the crystal structure in the layers.

Research paper thumbnail of Smoother Shank Profile for Atom Probe Specimens Prepared by the Multi-step Focused Ion Beam Milling

2006 19th International Vacuum Nanoelectronics Conference, 2006

Focused ion beam (FIB) milling has been successfully used to prepare a range of atom probe specim... more Focused ion beam (FIB) milling has been successfully used to prepare a range of atom probe specimens from metal alloys at site specific locations such as grain boundaries, thin ribbons, powders, and multilayer film materials. Commonly employed, 3-step process generates ledges that act as a stress concentration sites at the shank of the specimens. Smoother shank profile of the specimen is therefore desirable, so as to reduce the chance of specimen failure at such points. In this work, an improved method to fabricate the specimens from planar multilayer thin films was presented. The films were deposited onto etched Si posts, prepared by the lithographic patterning of a Si wafer. Capping layers (e.g. Cu, Ni, and Fe) were deposited on top to protect the films of interest from implantation damage caused by the high energy ion beams. Individual posts were attached to the tip of sharpened metal wires, and subsequently sharpened by ion milling in a FEI FIB 200 instrument without further Pt deposition required

Research paper thumbnail of Atomic Scale Study Of Precipitate / Matrix Interfaces in a Metallic Alloy

MRS Proceedings, 1997

ABSTRACTThe study of phase transformations involves making assumptions about interfaces within a ... more ABSTRACTThe study of phase transformations involves making assumptions about interfaces within a material in order to apply mathematical models. An example of this is the Gibbs classical theory of nucleation and growth which is based upon the assumption that the precipitate / matrix interface is sharp. Recent developments in atom probe microscopy have made it possible for the first time to characterize complex three-dimensional internal interfaces within materials to sub-nanometre accuracy. We have used the OPoSAP (Optical Position Sensitive Atom Probe) to characterize the precipitate / matrix interface in the dilute Cu-Co system which is a model alloy for the study of homogeneous nucleation and growth. Interface widths derived from radial composition profiles were measured to be 0.9 ± 0.2 nm in size. The effects of thermal energy, positioning inaccuracies, and statistical limitations on the measurement of interface widths are examined through the use of mathematical models and comp...

Research paper thumbnail of Summary of Discussion at the 1ST Workshop on 3-DIMENSIONAL Atom-Probe Analysis-Its Present and Future

Research paper thumbnail of Characterization of Segregation and Precipitation at Grain Boundaries in Thermally Aged Pressure Vessel Steels

2006 19th International Vacuum Nanoelectronics Conference, 2006

... Vessel Steels G. Shal*, S. Hirosawa2, A. MorleyI, A. Cerezol, GDW Smith', D. Ellis3 and ... more ... Vessel Steels G. Shal*, S. Hirosawa2, A. MorleyI, A. Cerezol, GDW Smith', D. Ellis3 and T Williams3 2 ... DE21 7XX * Corresponding author: tel: +44 1865 273711, fax: +44 1865 273789, e-mail:gang.sha@materials.ox.ac.uk. Grain ...

Research paper thumbnail of Numerical modelling of mass resolution in a scanning atom probe

Research paper thumbnail of Einzel lenses in atom probe designs