Temperature dependence of the anisotropy of amorphous NdCo5 thin films (original) (raw)
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Uniaxial magnetic anisotropy for thin Co films on glass studied by magnetooptic Kerr effect
Journal of Applied Physics, 2011
Thin Co films of different thickness deposited on glass are investigated by magnetooptic Kerr effect to study the uniaxial magnetic anisotropy of these films. The direction of the uniaxial magnetic anisotropy is determined from the azimuthal dependence of the magnetic remanence and differs with increasing thickness of the Co film investigated by x-ray reflectivity. Our experiments reveal that preparation conditions like temperature, deposition rate, or obliqueness of deposition cannot be the reason for this rotation effect of the uniaxial magnetic anisotropy. Also, strain in the substrate and possible textures in the film structure can be excluded as the origin of the magnetic behavior as studied by grazing incidence wide angle x-ray scattering. Thus, probably only the substrate shape in connection with the amorphous or polycrystalline film structure can explain the rotation of the uniaxial magnetic anisotropy. V
Perpendicular Magnetic Anisotropy in Co<sub>2</sub>FeAl Thin Films: Effect of Annealing Temperature
IEEE Transactions on Magnetics, 2015
In this paper, we show that perpendicular magnetic anisotropy can be achieved in polycrystalline Ni 80 Fe 20 films on MgO underlayers grown on thermally oxidized Si substrates. The perpendicular magnetic anisotropy is already present in the as-deposited films and preserved after thermal annealing. This paper points out the crucial role of the capping layer on the perpendicular magnetic anisotropy stabilization. By changing the nature of the capping from MgO, V, Nb to Ta, the value of the surface anisotropy constant is increased from 0.3 ± 0.05 erg/cm 2 in the case of the MgO to 0.79 ± 0.06 erg/cm 2 in the case of the Ta capping, respectively. For Ta capped samples, the perpendicular magnetization is achieved for Ni 80 Fe 20 films with an effective thickness below 1.1 nm.
Magnetic properties of dc magnetron sputtered and evaporated amorphous films
The European Physical Journal B, 2002
Compositions of Fe81B13.5Si3.5C2, Fe67Co18Si1B14 and Fe5.85Co72.15Mo2B15Si5 were deposited on to rigid and flexible substrates for the first time using a dc sputtering source as part of a novel Rotating Cryostat (RC). The films sputtered on silicon and glass show only isotropic magnetisation, whereas those sputtered on a polyimide (Kapton TM ) substrate exhibited either isotropic or anisotropic magnetisation depending upon composition. Similar findings were obtained for equivalent evaporated films.
Journal of Magnetism and Magnetic Materials, 1996
We have studied the in-plane magnetic anisotropy in polycrystalline cobalt films, which were obliquely deposited by e-beam evaporation in UHV at T~ = 300 K. Three film series were studied, with average film thicknesses t = 15, 45 and 100 nm. For all cases, the incidence angle of the vapor beam with respect to the surface normal was c~ = 0, 30, 40, 50, 60 and 70 °. At normal incidence, the anisotropy and the coercive fields were found to be H K = 15-25 Oe, and H c-25 Oe, independent of the film thickness. In all series it has been observed that, as c¢ increases, the easy axis of in-plane anisotropy switches from perpendicular to parallel with respect to the incidence plane of atoms during film deposition. For t = 15 nm, such a transition occurs at a, = 70 °, whereas for larger values of t we found that a t-60 °. At constant film thicknesses, H~c and H e increase with increasing or; the lower the film thickness, the sharper this effect, e.g. for c~ = 40 °, and t = 100, 45 and 15 nm, IlK= 15, 30 and 150 Oe, respectively. We analyzed two possible contributions to this effect: the shape anisotropy and the magnetocrystalline anisotropy (texture). At low film thicknesses the former becomes dominant. In order to understand the effect of oblique incidence on the in-plane easy axis location we studied the polar plot of reduced remanence m r as a function of both the angle a (between the surface normal and the vapor beam) and the angle 3' (between the in-plane applied field and the normal to the incidence plane of atoms during deposition). The behavior of mr(a, T) for a = 10 ° and 70 ° is reminiscent of that predicted by the coherent-rotation Stoner and Wohlfarth model, although fallback processes are observed. We found that the films tend to be magnetically isotropic for a = 60 °, whereas they are highly anisotropic for a = 10 °.
Journal of Applied Physics, 2012
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Magnetotransport and magnetic properties of amorphous \mathrm{NdNi}_5$$ thin films
Scientific Reports, 2020
NdNi 5 is an intermetallic compound with a bulk Curie temperature (T Curie) of 6-13 K. While existing studies have focused on NdNi 5 crystals, amorphous thin-films of NdNi 5 are potentially important since they would be magnetically soft without magnetocrystalline anisotropy, meaning that small external magnetic fields could reverse the direction of their magnetization. Here, we report NdNi 5 thin-films with a thickness in the 5-200 nm range, deposited by DC magnetron sputtering onto Si(100). Films are amorphous with a weak temperature-dependent resistivity with values ranging between 150 and 300 µ cm. By means of noise spectroscopy, by analyzing the time-dependence of fluctuationinduced voltages, it is found that at low temperatures the resistance fluctuations are due to the Kondo effect. Volume magnetometry indicates T Curie = 70 K with a magnetic coercive field of 30 mT at 5 K for a 125-nm-thick film. The results are promising for the development of Ferromagnet(F)/ Superconductor(S)/Ferromagnet(F) pseudo spin-valve devices based on amorphous NdNi 5 thin films. Spintronics is a major field of research in condensed matter physics 1. The capability to create and manipulate electronic spin currents enables to realize spin-based devices which, compared to their traditional charge-based counterpart, can be faster and demand lower power 1. The birth of spintronics traces back to the discovery of giant magnetoresistance (GMR) in Fe/Cr synthetic antiferromagnetic multilayers in which the electrical resistance increases when the magnetization in the magnetic layers changes from a parallel to an antiparallel alignment 2,3. A large number of material systems have been proposed for spintronics 4 including superconductors in conjunction with magnetic materials. This has paved the way for superconducting spintronics, which has potential to lead to the development of circuits that are more energy efficient, meaning that they should generate less heat and require low power for their functioning 5,6. In particular, a ferromagnet with a small value of the coercive field, H c , can be easily tuned in its magnetic properties, going from a state in which the magnetization, M, is zero when the applied external magnetic field H is equal to H c to a state in which, for H > H c , M = 0. In superconducting/ ferromagnetic (S/F) systems, this property can push the S/F system from the normal to superconducting state at low temperatures. Such a system can be used as a superconducting valve, since it can be switched between a superconducting (ON) and a normal (OFF) state by controlling the value of H. NdNi 5 is an intermetallic compound belonging to the RENi 5 (RE = Rare-earth) series. In bulk form, it is characterized by a large magnetocrystalline anisotropy, with the easy (hard) axis lying along the a axis within the hexagonal plane (the c axis) and an a axis (c axis) magnetization at 35 T of 3.3 μ B /f.u. (1.65 μ B /f.u.) 7,8 , and a T Curie in the range of 6-13 K 8-11. Here μ B is the Bohr magneton. In order to be used in conjunction with superconductors such as Nb (T c ∼ 9 K, T c is the superconducting transition temperature) or NbN (T c ∼ 15 K), the most frequently used materials in superconducting electronics, it is crucial to realize good quality NdNi 5 thin films because their availability may enable the design of dedicated transport experiments based on heterostructures operating as S/F-based devices. However, currently NdNi 5 is only available in crystal form 8,11,12 and, to the best of our knowledge, thin films have not been fabricated. Furthermore, it would be useful to obtain non-crystalline NdNi 5 films since amorphous magnetic materials are typically characterized by narrow hysteresis loops. This makes possible to use very small external magnetic fields to change their magnetic properties and in particular
Tunable perpendicular magnetic anisotropy in GdFeCo amorphous films
Journal of Magnetism and Magnetic Materials, 2013
We report the compositional and temperature dependence of magnetic compensation in amorphous ferrimagnetic Gd x Fe 93−x Co 7 alloy films. Magnetic compensation is attributed to the competition between antiferromagnetic coupling of rare-earth (RE) with transition-metal (TM) ions and ferromagnetic interaction between the TM ions. The low-Gd region of x between 20 and 34 was found to exhibit compensation phenomena characterized by a low saturation magnetization and perpendicular magnetic anisotropy (PMA) near the compensation temperature. Compensation temperature was not observed in previously unreported high-Gd region of x=52-59, in qualitative agreement with results from recent model calculations. However, low magnetization was achieved at room temperature, accompanied by a large PMA with coercivity reaching ~6.6 kOe. The observed perpendicular magnetic anisotropy of amorphous GdFeCo films probably has a structural origin consistent with certain aspects of the atomic-scale anisotropy. Our findings have broadened the composition range of transition metal-rare earth alloys for designing PMA films, making it attractive for tunable magnetic anisotropy in nanoscale devices.
Journal of Magnetism and Magnetic Materials, 1996
The magnetic properties of if-sputtered amorphous (Co93Zr7)lOo_xNd x thin films with 0 < x < 3.5 were investigated by transverse biased initial susceptibility (TBIS) measurements at both film/air and glass/film interfaces. The films exhibit a very well defined in-plane uniaxial anisotropy with negligible long-range fluctuations. A clear relationship could be established between Ku and Klo¢, data which is discussed in terms of the single-ion anisotropy of the Nd ions. Although the value of H k is the same at both interfaces, the as-determined ripple constants were found to be slightly different. This last result is believed to be related to some local defect, the origin of which is also advanced.
Anisotropy and magneto-optical properties of sputtered Co/Ni multilayer thin films
IEEE Transactions on Magnetics, 1994
AbsrraclSeveral series of sputtered Co/Ni multilayer thin films have been investigated. The volume and interface contributions to the magnetic anisotropy were determined from magnetization measurements, and the interface anisotropy, 6 = 0.23 f 0.03 erg/cm2, was found to support perpendicular magnetic anisotropy. The anisotropy constant, K, increased with the Au buffer layer thickness, indicating the buffer layer was crucial to the perpendicular magnetic anisotropy. The polar Kerr rotation and coercivity as a function of temperature, and room temperature magnetooptical figure of merit are presented in this paper.