Perpendicular magnetic anisotropy and magneto-optical Kerr effect of vapor-deposited Co/Pt-layered structures

Zeper, W. B.; Greidanus, F.J.A.M.; Carcia, P. F.; Fincher, C. R.

doi:10.1063/1.343189

Cited by 594 publications

(135 citation statements)

References 15 publications

Supporting

Mentioning

130

Contrasting

Unclassified

Order By: Relevance

“…Each ferromagnetic disk consists of a 2.5 nm Pt buffer layer covered with a ð0:4 nm Co=1:0 nm PtÞ 10 multilayer with magnetization perpendicular to the sample surface [18]. A 50 nm thick superconducting Pb film with critical temperature T c ¼ 7:2 K was evaporated on top, covering the whole substrate, i.e., the patterned area with magnetic disks and all the surrounding unpatterned region.…”

Section: Experimental Details and Sample Layoutmentioning

confidence: 99%

Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

et al. 2011

View full text Add to dashboard Cite

If a magnet of microscopic dimensions is brought in close proximity to a superconductor, the quantized nature of their interaction due to the creation of flux quanta in the superconducting system becomes noticeable. Herein, we directly image, via scanning Hall microscopy, the vortex-antivortex pairs in a superconducting film created by micromagnets. The number of antivortices at equilibrium conditions can be changed either by tuning the magnetic moment of the magnets or by annihilation with externally induced vortices. We demonstrate that small ac field excitations shake the antivortices sitting next to the micromagnets whereas no sizable motion is observed for the vortices sitting on top of the magnets, clearly revealing the different mobility of these two vortex species. A metastable state, which is obtained by applying a field after the system has been cooled down below the superconducting transition, shows a complex graded distribution of coexisting vortices and antivortices forming an intertwined critical state.

show abstract

Section: Experimental Details and Sample Layoutmentioning

confidence: 99%

Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Their attractive properties include perpendicular magnetic anisotropy (PMA) and a large polar magneto-optic Kerr effect (MOKE) at short wavelengths 4 . More recently Co/Pt has become an interesting system for the study of the physics of domain walls (DWs) [5][6][7][8] , and spin torque [9][10][11][12][13] .…”

mentioning

confidence: 99%

Effect of substrate temperature on the magnetic properties of epitaxial sputter-grown Co/Pt

Mihai

Whiteside

Canwell

et al. 2013

Applied Physics Letters

View full text Add to dashboard Cite

Epitaxial Co/Pt films have been deposited by dc-magnetron sputtering onto heated C-plane sapphire substrates. X-ray diffraction, the residual resistivity and transmission electron microscopy indicate that the Co/Pt films are highly ordered on the atomic scale. The coercive field and the perpendicular magnetic anisotropy increase as the substrate temperature is increased from 100-250C during deposition of the Co/Pt. Measurement of the domain wall creep velocity as a function of applied magnetic field yields the domain wall pinning energy, which scales with the coercive field. Evidence for an enhanced creep velocity in highly ordered epitaxial Co/Pt is found. 2Co/Pt multilayers have been studied for a number of years 1,2 , initially because of their potential as magneto-optical recording media 3 . Their attractive properties include perpendicular magnetic anisotropy (PMA) and a large polar magneto-optic Kerr effect (MOKE) at short wavelengths 4 . More recently Co/Pt has become an interesting system for the study of the physics of domain walls (DWs) [5][6][7][8] , and spin torque [9][10][11][12][13] . The PMA leads to the formation of narrow, nanometre-scale DWs, and the large polar Kerr effect is convenient for measuring the DW motion. However, DWs tend to pin at grain boundaries in the polycrystalline Co/Pt that is typically used in these studies 9 , and this is an issue not only for investigations of the fundamental physics of DWs but also for future devices which may depend upon reliable DW motion, such as racetrack memory 14 . Epitaxial Co/Pt, in which the density of grain boundaries is minimised, could provide a solution to this problem. Ideally, however, the method of multilayer deposition should be compliant with industrial processes.Sputtering is a convenient, cost-effective technique for thin film deposition and may be used to grow films epitaxially if a single crystal substrate is heated to an appropriate temperature.In order to obtain PMA in epitaxial Co/Pt, the films are required to grow in the (111)-orientation 15 , and (111) texture was first seen in sputtered Co/Pt in 1993 16 . While there have been studies of Co/Pt superlattices 17 and Pt/Co/Pt sandwiches 18 grown by sputtering, there has been no optimisation of sputtered epitaxial Co/Pt (111) for DW devices. Here we show how the substrate temperature may be used to tune the magnetic properties of epitaxial Co/Pt grown on sapphire.First, the growth of Pt on C-plane (0001) sapphire was optimised. A 60 nm Pt film was deposited at various substrate temperatures in the range 400-700C. High angle X-ray scans all had a clear peak between 39.5 and 40, indicating (111) structure (see Figure 1). The 3 peak was largest and the satellite peaks were best defined for a deposition temperature of 500C indicating that at this temperature the crystal quality of the film was highest. It was also found that overnight annealing of the sapphire substrate at 700 C improved film quality. X-ray reflectivity curves were measured from Pt films deposited both after a s...

show abstract

“…The resulting magnetic structures show well-defined out-of-plane magnetization. 12 Both templates are covered by a 5-nm-thick Si layer followed by a superconducting Al layer of 50 nm thickness. Since the Al film is insulated from the ferromagnetic substrate, the interaction between ferromagnet and superconductor is electromagnetic in origin with negligible proximity effects.…”

mentioning

confidence: 99%

Magnetic confinement of the superconducting condensate in superconductor-ferromagnet hybrid composites

et al. 2007

View full text Add to dashboard Cite

The influence of an inhomogeneous magnetic field on the magnetoresistance of thin Al films, used in different superconductor-ferromagnet hybrids, has been investigated. Two contrasting magnetic textures with out-of-plane magnetization are explored: namely, ͑i͒ a plain film in a multidomain state and ͑ii͒ an array of microsized dots. The stray fields of the ferromagnetic structures confine the superconducting condensate and, accordingly, modify the condition for the nucleation of superconductivity. By switching between different magnetic states of the ferromagnet, this confinement can be tuned at will, thereby reversibly changing the dependence of the critical temperature T c on an external magnetic field H. In particular, continuous evolution from a conventional linear T c ͑H͒ dependence with a single maximum to a reentrant superconducting phase boundary with multiple T c peaks has been demonstrated. The localization of a particle in a restricted volume is known to lead to a discrete energy spectrum due to the particle's wave nature. In some cases the trapping potential can be created artificially in a controlled way ͑e.g., in quantum dots and wells͒, and the geometry-dependent structure of the energy levels provides a convenient way to control the optical and transport properties of such objects. 1 Remarkably, some basic concepts of standard quantum mechanics ͑includ-ing the confinement of the wave function͒ can also be applied to more complicated systems, like superconductors, in which a quantum condensate consisting of paired electrons develops. In this case, the energy of the lowest Landau level, E LLL ͑H͒, where H is the external magnetic field, determines the critical temperature T c ͑H͒ at which superconductivity nucleates. 2 Due to the strong dependence of E LLL ͑H͒ on the imposed confinement, T c ͑H͒ for superconducting microstructures and nanostructures differs significantly from that observed in bulk superconductors. 3 Unfortunately, once this "geometrical" constraint is created, the trapping potential cannot be modified any longer.However, the use of superconductor-ferromagnet ͑S-F͒ hybrids provides an appealing alternative to localize superconducting Cooper pairs. In such S-F hybrids the proximity effect 4 as well as the stray fields of the ferromagnet 5 play an important role in changing the superconducting properties. A magnetic template which creates a nonuniform magnetic field distribution is able to localize the superconducting condensate ͑or normal electrons 6 ͒. Such a modulated field profile can result in exotic shapes of the T c ͑H͒ phase boundary for S-F hybrids, revealing a simple shift of the T c maximum towards a certain magnetic field ͑so called field-induced-superconductivity 7,8 ͒ or a more complicated nonmonotonic T c ͑H͒ dependence with two maxima ͑reen-trant superconductivity 9-11 ͒, and are commonly explained in terms of magnetic field compensation effects. Indeed, for thin superconducting films, placed in a nonuniform magnetic field, superconductivity first nucleates near the ͉B...

show abstract

Perpendicular magnetic anisotropy and magneto-optical Kerr effect of vapor-deposited Co/Pt-layered structures

Cited by 594 publications

References 15 publications

Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

Imaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks

Effect of substrate temperature on the magnetic properties of epitaxial sputter-grown Co/Pt

Magnetic confinement of the superconducting condensate in superconductor-ferromagnet hybrid composites

Contact Info

Product

Resources

About