Microstructural Dependence of the Perpendicular Magnetic Anisotropy in Co-Pt Alloys

1993 ◽  
Vol 313 ◽  
Author(s):  
E. E. Marinero ◽  
R. F. C. Farrow ◽  
G. R. Harp ◽  
R. H. Geiss ◽  
J. A. Bain ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Temperature Dependence ◽  
Elevated Temperatures ◽  
Perpendicular Magnetic Anisotropy ◽  
Strong Temperature Dependence ◽  
Perpendicular Anisotropy ◽  
Chemical Ordering ◽  
Polycrystalline Alloys ◽  
Out Of Plane ◽  
Pt Alloys

ABSTRACTTo establish the structural origins of the perpendicular magnetic anisotropy in Co-Pt alloys, a variety of magnetic and structural characterization techniques have been utilized. We have determined that the development of out-of-plane magnetization in these alloys, strongly depends on growth temperature and in contrast to CO/Pt Multilayers, the highest anisotropics and coercivities are observed in polycrystalline alloys with negligible preferred crystallographic orientation. Lattice strain Measurements, surface roughness determination and crystal growth studies indicate that contributions from magnetostrictive and magnetostatic contributions to the perpendicular anisotropy in these alloys are not significant. H RTEM and synchrotron-based x-ray diffraction experiments, on the other hand, confirm the existence of ordered CoPt3 at elevated temperatures. We suggest that the strong temperature dependence of the perpendicular anisotropy is correlated to the onset of spontaneous chemical ordering during the growth which results in anisotropie pair ordering. A tentative model explaining this strong temperature dependence is described.

Thickness Dependent Perpendicular Magnetic Domain Patterns in Sputtered Epitaxial FePt (001) L10 Films

1998 ◽  
Vol 517 ◽  
Author(s):  
J.-U. Thiele ◽  
L. Folks ◽  
M. F. Toney ◽  
D. K. Weller
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetic Domain ◽  
Perpendicular Magnetic Anisotropy ◽  
Grazing Incidence ◽  
Anisotropy Constant ◽  
Exchange Constant ◽  
Stripe Domain ◽  
Chemical Ordering ◽  
Out Of Plane ◽  
Face Centered

AbstractThe present paper discusses the magnetic anisotropy and magnetic domain structure of highly ordered epitaxial FePt(001) films grown on Pt seeded MgO(001) substrates. These films were grown by dc-magnetron sputtering from a Fe50Pt50 alloy target at a substrate temperature of 550°C during deposition. Thicknesses were varied between 15 and 170 nm. The presence of the highly anisotropic face centered tetragonal L10 crystal structure with a maximum long range chemical ordering of 95% and a low degree of misorientations was confirmed by specular and grazing incidence X-ray diffraction measurements. For film thicknesses ≥ 50 nm in-plane and out-of-plane hysteresis measurements indicate large perpendicular magnetic anisotropy and at the same time low remanent magnetisation. Magnetic force microscopy reveals highly interconnected perpendicular stripe domain patterns. From their characteristic width, which is strongly dependent on the film thickness, a value of the dipolar length, D0, of 50 ±5 nm is derived. Assuming an exchange constant of 10-6 erg/cm, this value is consistent with an anisotropy constant Ku ∼ 1.108 erg/cc.

Strong Perpendicular Magnetic Anisotropy with High Thermal Stability in Annealed Co/Native Oxide/Pd Multilayers

2013 ◽  
Vol 634-638 ◽  
pp. 2506-2511
Author(s):  
Qin Li Lv ◽  
Jian Wang Cai ◽  
Tao Li
Keyword(s):  
Thermal Stability ◽  
Magnetic Anisotropy ◽  
Annealing Temperature ◽  
Perpendicular Magnetic Anisotropy ◽  
Anisotropy Field ◽  
High Thermal Stability ◽  
Native Oxide ◽  
Perpendicular Anisotropy ◽  
Sharp Transition ◽  
Out Of Plane

A novel perpendicular magnetic material was obtained in the annealed Co/native oxide/Pd multilayer films. Upon thermal annealing in a vacuum, a sharp transition of magnetic anisotropy from in-plane to out-of-plane is observed for the Co/native oxide/Pd multilayers with 20 Å Co layers. These annealed Co/native oxide/Pd multilayers possess extremely large effect perpendicular anisotropy field (Heff) and perpendicular anisotropy energy (Ku), with the maximum Heff of 17 kOe and Ku of 5.1×106 erg/cm3 obtained in the annealed Co(20 Å)/native oxide/Pd(10 Å) multilayers. Moreover, the large perpendicular magnetic anisotropy sustains with annealing temperature varying from 200°C to 400°C, indicative of high thermal stability. The present results open the way to a third alternative for the realization of thermally stable perpendicular magnetic electrodes of tunnel junctions.

scholarly journals Origin of perpendicular magnetic anisotropy in amorphous thin films

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniel Lordan ◽  
Guannan Wei ◽  
Paul McCloskey ◽  
Cian O’Mathuna ◽  
Ansar Masood
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Perpendicular Magnetic Anisotropy ◽  
Functional Materials ◽  
Spin Reorientation ◽  
Amorphous Films ◽  
Amorphous Thin Films ◽  
Magnetic Performance ◽  
Out Of Plane ◽  
Sputtering Pressure

AbstractThe emergence of perpendicular magnetic anisotropy (PMA) in amorphous thin films, which eventually transforms the magnetic spins form an in-plane to the out-of-plane configuration, also known as a spin-reorientation transition (SRT), is a fundamental roadblock to attain the high flux concentration advantage of these functional materials for broadband applications. The present work is focused on unfolding the origin of PMA in amorphous thin films deposited by magnetron sputtering. The amorphous films were deposited under a broad range of sputtering pressure (1.6–6.2 mTorr), and its effect on the thin film growth mechanisms was correlated to the static global magnetic behaviours, magnetic domain structure, and dynamic magnetic performance. The films deposited under low-pressure revealed a dominant in-plane uniaxial anisotropy along with an emerging, however feeble, perpendicular component, which eventually evolved as a dominant PMA when deposited under high-pressure sputtering. This change in the nature of anisotropy redefined the orientation of spins from in-plane to out-of-plane. The SRT in amorphous films was attributed to the dramatic change in the growth mechanism of disorder atomic structure from a homogeneously dispersed to a porous columnar microstructure. We suggest the origin of PMA is associated with the columnar growth of the amorphous films, which can be eluded by a careful selection of a deposition pressure regime to avoid its detrimental effect on the soft magnetic performance. To the author’s best knowledge, no such report links the sputtering pressure as a governing mechanism of perpendicular magnetisation in technologically important amorphous thin films.

scholarly journals Temperature-Driven Spin Reorientation Transition in CoPt/AlN Multilayer Films

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Wupeng Cai ◽  
Shinji Muraishi ◽  
Ji Shi ◽  
Yoshio Nakamura ◽  
Wei Liu ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Mean Field ◽  
Multilayer Films ◽  
Spin Reorientation ◽  
Strong Temperature Dependence ◽  
Mean Field Model ◽  
Spin Reorientation Transition ◽  
Magnetoelastic Effect ◽  
Out Of Plane ◽  
Interface Anisotropy

Spin reorientation transition phenomena from out-of-plane to in-plane direction with increasing temperature are observed for the 500°C annealed CoPt/AlN multilayer films with different CoPt layer thicknesses. CoPt-AlN interface and volume anisotropy contributions, favoring out-of-plane and in-plane magnetization, respectively, are separately determined at various temperatures. Interface anisotropy exhibits much stronger temperature dependence than volume contribution, hence the temperature-driven spin reorientation transition occurs. Interface anisotropy in this work consists of Néel interface anisotropy and magnetoelastic effect. Magnetoelastic effect degrades rapidly and changes its sign from positive to negative above 200°C, because of the involvement of stress state in CoPt films with temperature. By contrast, Néel interface anisotropy decays slowly, estimated from a Néel mean field model. Thus, the strong temperature dependence of CoPt-AlN interface anisotropy is dominated by the change of magnetoelastic effect.

scholarly journals Strain-induced perpendicular magnetic anisotropy and Gilbert damping of Tm3Fe5O12 thin films

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Oana Ciubotariu ◽  
Anna Semisalova ◽  
Kilian Lenz ◽  
Manfred Albrecht
Keyword(s):  
Film Thickness ◽  
Magnetic Anisotropy ◽  
Tensile Strain ◽  
Easy Axis ◽  
Perpendicular Magnetic Anisotropy ◽  
Gilbert Damping ◽  
Sample Plane ◽  
Iron Garnets ◽  
Out Of Plane ◽  
Magnetic Easy Axis

AbstractIn the attempt of implementing iron garnets with perpendicular magnetic anisotropy (PMA) in spintronics, the attention turned towards strain-grown iron garnets. One candidate is Tm3Fe5O12 (TmIG) which possesses an out-of-plane magnetic easy axis when grown under tensile strain. In this study, the effect of film thickness on the structural and magnetic properties of TmIG films including magnetic anisotropy, saturation magnetization, and Gilbert damping is investigated. TmIG films with thicknesses between 20 and 300 nm are epitaxially grown by pulsed laser deposition on substituted-Gd3Ga5O12(111) substrates. Structural characterization shows that films thinner than 200 nm show in-plane tensile strain, thus exhibiting PMA due to strain-induced magnetoelastic anisotropy. However, with increasing film thickness a relaxation of the unit cell is observed resulting in the rotation of the magnetic easy axis towards the sample plane due to the dominant shape anisotropy. Furthermore, the Gilbert damping parameter is found to be in the range of 0.02 ± 0.005.

Study of Perpendicular Magnetic Anisotropy in Co/Au Multilayer Probed by Magnetic Compton Profile

2013 ◽  
Vol 596 ◽  
pp. 8-14 ◽  
Author(s):  
Kosuke Suzuki ◽  
Masaki Hayata ◽  
Katsuhiko Minegishi ◽  
Ryosuke Kondoh ◽  
Tadashi Kato ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Cluster Model ◽  
Perpendicular Magnetic Anisotropy ◽  
Volume Ratio ◽  
Main Role ◽  
Compton Profile ◽  
Perpendicular Anisotropy ◽  
Model Calculations ◽  
Secondary Role

Magnetic Compton profiles (MCPs) of Co/Au multilayers have been measured and analyzed by DV-Xαcluster model calculations from a viewpoint of perpendicular magnetic anisotropy (PMA). The PMA and the MCPs are discussed for the presently obtained results for Co/Au, along with the previously obtained results for Co/Pd and Co/Pt. A Co/Au multilayer shows a weak PMA which is caused by |m|=1 states of Co 3d electrons at a smooth Co/Au interface. The increase of the interface-to-volume ratio plays the main role in determining the perpendicular anisotropy in Co/Au multilayers. The strain of a Co layer can have a secondary role in determining the magnetic anisotropy in Co/Au multilayers, although the strain dominates PMA in the case of Co/Pd and Co/Pt multilayers.

Substrate-Deposition-Teiimperatijre Dependence of Perpendicular Magnetic Anisotropy in (Fe/Pt) Compositionally-Modulated Films

1991 ◽  
Vol 232 ◽  
Author(s):  
S. Iwata ◽  
S. S. P. Parkin ◽  
H. Nuri ◽  
T. Suzuki
Keyword(s):  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Saturation Magnetization ◽  
Systematic Study ◽  
Deposition Temperature ◽  
Major Part ◽  
Perpendicular Magnetic Anisotropy ◽  
Perpendicular Anisotropy ◽  
Elastic Effect

ABSTRACTA systematic study on magnetic properties of (Fc/Pt) compositionally-modulated films as a function of substrate-deposition-temperature has been carried out. For films with (2.5ÅFe/18ÅPt)×40, the intrinsic perpendicular magnetic anisotropy Ku is found to increase with decreasing temperature for all the sarmples deposited at temperatures from -114 °C to 220°C during deposition. The higher the substrate-deposition-temperature, the larger the Ku values become. This result implies a possible contribution from the magne to-elastic effect to the total anisotropy. However, a major part responsible for the perpendicular anisotropy may be found in other mechanisms. The saturation magnetization is found to exceed the value for pure Fe at temperatures lower than 180K.

Quenching and temperature dependence of perpendicular magnetic anisotropy of Pt/Co multilayers

2015 ◽  
Author(s):  
Yonggang Xu ◽  
Xiaolin Zhao ◽  
Meng Lv ◽  
Guolin Yu ◽  
Ning Dai ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Temperature Dependence ◽  
Perpendicular Magnetic Anisotropy

scholarly journals Violation of the T−1 Relationship in the Lattice Thermal Conductivity of Mg3Sb2 with Locally Asymmetric Vibrations

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yifan Zhu ◽  
Yi Xia ◽  
Yancheng Wang ◽  
Ye Sheng ◽  
Jiong Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Dependence ◽  
Lattice Thermal Conductivity ◽  
Elevated Temperatures ◽  
Low Frequency ◽  
Strong Temperature Dependence ◽  
Depth Analysis ◽  
Force Profile ◽  
Phonon Renormalization ◽  
Increasing Temperature

Most crystalline materials follow the guidelines of T−1 temperature-dependent lattice thermal conductivity (κL) at elevated temperatures. Here, we observe a weak temperature dependence of κL in Mg3Sb2, T−0.48 from theory and T−0.57 from measurements, based on a comprehensive study combining ab initio molecular dynamics calculations and experimental measurements on single crystal Mg3Sb2. These results can be understood in terms of the so-called “phonon renormalization” effects due to the strong temperature dependence of the interatomic force constants (IFCs). The increasing temperature leads to the frequency upshifting for those low-frequency phonons dominating heat transport, and more importantly, the phonon-phonon interactions are weakened. In-depth analysis reveals that the phenomenon is closely related to the temperature-induced asymmetric movements of Mg atoms within MgSb4 tetrahedron. With increasing temperature, these Mg atoms tend to locate at the areas with relatively low force in the force profile, leading to reduced effective 3rd-order IFCs. The locally asymmetrical atomic movements at elevated temperatures can be further treated as an indicator of temperature-induced variations of IFCs and thus relatively strong phonon renormalization. The present work sheds light on the fundamental origins of anomalous temperature dependence of κL in thermoelectrics.

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