Investigations of the Magnetic Perpendicular Exchange Bias in L10 FePt/NiO Bilayer Thin Films

MRS Advances ◽  
2018 ◽  
Vol 3 (47-48) ◽  
pp. 2893-2898
Author(s):  
Zachary B. Leuty ◽  
Robert A. Mayanovic
Keyword(s):  
Thin Films ◽  
Exchange Bias ◽  
Giant Magnetoresistance ◽  
Magnetic Layer ◽  
Ferromagnetic Layer ◽  
Random Access ◽  
Perpendicular Magnetic Anisotropy ◽  
Magnetic Sensors ◽  
Magnetic Storage ◽  
Cross Sectional

ABSTRACTWe report on the exploration of perpendicular exchange bias in iron platinum/nickel oxide (FePt/NiO) bilayer thin films grown using pulsed laser deposition (PLD) on MgO (100) substrates. Exchange bias is an important property for giant magnetoresistance, and, as such has promise for applications in spin valves, magnetic sensors and magnetic random access memory. The magnetic L10 phase of FePt is known for having high perpendicular magnetic anisotropy, tunable coercivity/grain size and large magnetic storage density. The FePt layer was first deposited directly on MgO, followed by the deposition of the NiO layer on top of the FePt layer. The coercivity of the L10 FePt layer was tuned during growth to form a hard or soft magnetic layer. The FePt/NiO thin films grown for this study exhibit perpendicular exchange bias at 5K, as quantified using our SQUID measurements. XRD confirms parallel plane ordering between the MgO (200), FePt (002) and NiO (111) atomic planes while cross sectional TEM confirms the epitaxial growth of L10-FePt(001)<100>//MgO(100)<001> and the preferential growth of NiO on top of the FePt. Films of only FePt were grown to examine the surface architecture of the ferromagnetic layer and thus the interface of the FePt/NiO bilayer. The results from our XRD, TEM and magnetometry characterization of the FePt films and FePt/NiO bilayer thin films will be discussed.

scholarly journals Exchange Bias Effect in LaFeO3: La0.7Ca0.3MnO3 Composite Thin Films

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1125
Author(s):  
Feng Wang ◽  
Wei Fu ◽  
Chengming Jiang ◽  
Junxiao Li ◽  
Jijie Huang
Keyword(s):  
Thin Films ◽  
Exchange Bias ◽  
Physical Property ◽  
Bias Field ◽  
Magnetic Storage ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Composite Thin Films ◽  
Composition Variation ◽  
Two Phases

Composite thin films arouse great interests owing to the multifunctionalities and heterointerface induced physical property tailoring. The exchange bias effect aroused from the ferromagnetic (FM)–antiferromagnetic (AFM) heterointerface is applicable in various applications such as magnetic storage. In this work, (LaFeO3)x:(La0.7Ca0.3MnO3)1−x composite thin films have been deposited via pulsed laser deposition (PLD) and the exchange bias effect was investigated. In such system, LaFeO3 (LFO) is an antiferromagnet while La0.7Ca0.3MnO3 (LCMO) is a ferromagnet, which results in the exchange bias interfacial coupling at the FM/AFM interface. The composition variation of the two phases could lead to the exchange bias field (HEB) tuning in the composite system. This work demonstrates a new composite thin film system with FM-AFM interfacial exchange coupling, which could be applied in various spintronic applications.

scholarly journals Ferromagnetic Resonance Studies in Magnetic Nanosystems

2021 ◽  
Vol 7 (9) ◽  
pp. 126
Author(s):  
David S. Schmool ◽  
Daniel Markó ◽  
Ko-Wei Lin ◽  
Aurelio Hierro-Rodríguez ◽  
Carlos Quirós ◽  
...  
Keyword(s):  
Thin Films ◽  
Ferromagnetic Resonance ◽  
Magnetic Layer ◽  
Perpendicular Magnetic Anisotropy ◽  
Magnetization Dynamics ◽  
Microwave Spectrometer ◽  
Depth Analysis ◽  
Ferromagnetic Layers ◽  
Recent Developments ◽  
Magnetic Spin

Ferromagnetic resonance is a powerful method for the study of all classes of magnetic materials. The experimental technique has been used for many decades and is based on the excitation of a magnetic spin system via a microwave (or rf) field. While earlier methods were based on the use of a microwave spectrometer, more recent developments have seen the widespread use of the vector network analyzer (VNA), which provides a more versatile measurement system at almost comparable sensitivity. While the former is based on a fixed frequency of excitation, the VNA enables frequency-dependent measurements, allowing more in-depth analysis. We have applied this technique to the study of nanostructured thin films or nanodots and coupled magnetic layer systems comprised of exchange-coupled ferromagnetic layers with in-plane and perpendicular magnetic anisotropies. In the first system, we have investigated the magnetization dynamics in Co/Ag bilayers and nanodots. In the second system, we have studied Permalloy (Ni80Fe20, hereafter Py) thin films coupled via an intervening Al layer of varying thickness to a NdCo film which has perpendicular magnetic anisotropy.

Control of the perpendicular magnetic anisotropy and perpendicular exchange bias in CoPt/CoOx thin films

2019 ◽  
Vol 484 ◽  
pp. 320-323 ◽  
Author(s):  
Chunjiao Pan ◽  
Hongyu An ◽  
Takashi Harumoto ◽  
Zhengjun Zhang ◽  
Yoshio Nakamura ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Exchange Bias ◽  
Perpendicular Magnetic Anisotropy

Perpendicular Magnetic Anisotropy in Co-Based Full Heusler Alloy Thin Films

SPIN ◽  
2015 ◽  
Vol 05 (04) ◽  
pp. 1540012 ◽  
Author(s):  
Y. Wu ◽  
X. G. Xu ◽  
J. Miao ◽  
Y. Jiang
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Heusler Alloy ◽  
Heusler Alloys ◽  
Random Access ◽  
Perpendicular Magnetic Anisotropy ◽  
Functional Materials ◽  
Research Area ◽  
High Spin Polarization ◽  
Full Heusler

Half-metallic Co-based full Heusler alloys have been qualified as promising functional materials in spintronic devices due to their high spin polarization. The lack of perpendicular magnetic anisotropy (PMA) is one of the biggest obstacles restricting their application in next generation ultrahigh density storage such as magnetic random access memory (MARM). How to induce the PMA in Co-based full Heusler alloy thin films has attracted much research interest of scientists. This paper presents an overview of recent progress in this research area. We hope that this paper would provide some guidance and ideas to develop highly spin-polarized Co-based Heusler alloy thin films with PMA.

Characterizations of the Perpendicular Magnetic Anisotropy in Ultrathin Films of Ta-CoFeB-MgO by X-Ray Photoelectron Spectroscopy

2013 ◽  
Vol 739 ◽  
pp. 61-65 ◽  
Author(s):  
Chih Wei Cheng ◽  
H.M. Chen ◽  
C.H. Shiue ◽  
Y.Y. Lin ◽  
Y.Y. Li ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Random Access ◽  
Perpendicular Magnetic Anisotropy ◽  
Magnetic Tunnel Junction ◽  
Dead Layer ◽  
X Ray ◽  
Bottom Structures

The high magnetic anisotropy may enhance the thermal stability of the magnetic tunnel junction of CoFeB/MgO/CoFeB, which is a promising candidate for the high performance magnetic random access memory (MRAM). However, the interface stabilized perpendicular magnetic anisotropy (PMA) is not completely understood at this moment. In this study, we fabricated separated top and bottom Ta-CoFeB-MgO thin films and found both structures showed strong PMA after a 300 °C post annealing. However, the top structure has thicker magnetic dead layer and much higher coercivity relative to the bottom structures. The asymmetry between the top and bottom Ta-CoFeB-MgO structures may be attributed to the crystalline structure and interface diffusion. X-ray photoelectron spectroscopy depth profile reveals that the boron diffuses mainly toward to the Ta side at CoFeB-Ta interface in both top and bottom structures. It is mainly Ta that appears at the CoFeB-MgO interface of top structure while it is TaOx that appears at the CoFeB-MgO interface of bottom structure. A detailed discussion about the chemical states at the interface in Ta-CoFeB-MgO thin films will be given.

A technique to prepare cross-sectional TEM specimens of semiconducting devices

1986 ◽  
Vol 44 ◽  
pp. 742-743
Author(s):  
A. K. Rai ◽  
P. P. Pronko
Keyword(s):  
Thin Films ◽  
Surface Region ◽  
Sample Surface ◽  
Specific Region ◽  
Cross Sectional ◽  
Thin Sections ◽  
The Past ◽  
Device Structures ◽  
Ion Implanted

Several techniques have been reported in the past to prepare cross(x)-sectional TEM specimen. These methods are applicable when the sample surface is uniform. Examples of samples having uniform surfaces are ion implanted samples, thin films deposited on substrates and epilayers grown on substrates. Once device structures are fabricated on the surfaces of appropriate materials these surfaces will no longer remain uniform. For samples with uniform surfaces it does not matter which part of the surface region remains in the thin sections of the x-sectional TEM specimen since it is similar everywhere. However, in order to study a specific region of a device employing x-sectional TEM, one has to make sure that the desired region is thinned. In the present work a simple way to obtain thin sections of desired device region is described.

Characterization of reactive phase formation in sputter-deposited Ni/Al multilayer thin films using TEM

1996 ◽  
Vol 54 ◽  
pp. 1000-1001
Author(s):  
G. Lucadamo ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Dark Field ◽  
Nickel Layer ◽  
Multilayer Thin Films ◽  
Cross Sectional ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Constant Heating

The subject of reactive phase formation in multilayer thin films of varying periodicity has stimulated much research over the past few years. Recent studies have sought to understand the reactions that occur during the annealing of Ni/Al multilayers. Dark field imaging from transmission electron microscopy (TEM) studies in conjunction with in situ x-ray diffraction measurements, and calorimetry experiments (isothermal and constant heating rate), have yielded new insights into the sequence of phases that occur during annealing and the evolution of their microstructure.In this paper we report on reactive phase formation in sputter-deposited lNi:3Al multilayer thin films with a periodicity A (the combined thickness of an aluminum and nickel layer) from 2.5 to 320 nm. A cross-sectional TEM micrograph of an as-deposited film with a periodicity of 10 nm is shown in figure 1. This image shows diffraction contrast from the Ni grains and occasionally from the Al grains in their respective layers.

TEM Study of Co/Pd and Co/Au Multilayers

1993 ◽  
Vol 51 ◽  
pp. 1036-1037
Author(s):  
A.E.M. De Veirman ◽  
F.J.G. Hakkens ◽  
W.M.J. Coene ◽  
F.J.A. den Broeder
Keyword(s):  
Magnetic Anisotropy ◽  
Ion Beam ◽  
Perpendicular Magnetic Anisotropy ◽  
Optical Recording ◽  
Magnetic Multilayer ◽  
Ion Beam Sputtering ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Beam Sputtering ◽  
Substrate Temperatures

There is currently great interest in magnetic multilayer (ML) thin films (see e.g.), because they display some interesting magnetic properties. Co/Pd and Co/Au ML systems exhibit perpendicular magnetic anisotropy below certain Co layer thicknesses, which makes them candidates for applications in the field of magneto-optical recording. It has been found that the magnetic anisotropy of a particular system strongly depends on the preparation method (vapour deposition, sputtering, ion beam sputtering) as well as on the substrate, underlayer and deposition temperature. In order to get a better understanding of the correlation between microstructure and properties a thorough cross-sectional transmission electron microscopy (XTEM) study of vapour deposited Co/Pd and Co/Au (111) MLs was undertaken (for more detailed results see ref.).The Co/Pd films (with fixed Pd thickness of 2.2 nm) were deposited on mica substrates at substrate temperatures Ts of 20°C and 200°C, after prior deposition of a 100 nm Pd underlayer at 450°C.

TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy

1993 ◽  
Vol 51 ◽  
pp. 1118-1119
Author(s):  
Pamela F. Lloyd ◽  
Scott D. Walck
Keyword(s):  
Thin Films ◽  
Sample Preparation ◽  
Room Temperature ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Ultra High Vacuum ◽  
Wear Testing ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Aerospace Applications

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.

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