Realize the method for perpendicular magnetic anisotropy in a kind of magnetoresistance effect
Technical field
The invention belongs to the magneto-electronics field, be specifically related to realize in a kind of magnetoresistance effect the method for perpendicular magnetic anisotropy.
Technical background
Exchange biased, be meant ferromagnetic (FM)/antiferromagnetic (AFM) duplicature system is through after the magnetic field cooling, coercive force H
cObviously be enhanced, magnetic hysteresis loop has departed from initial point simultaneously.The FM/AFM duplicature is exchange biased to be that high density magnetic recording is read first-class giant magnetoresistance magnetic field sensor, reached the core texture in the magnetic random memory unit magnetoelectronic devices such as (MRAM).In above-mentioned application, people utilize ferromagnetic/antiferromagnetic duplicature parallel exchange biased.In fact, not only can utilize the enhancing of parallel exchange biased realization intra-face anisotropy, and can utilize vertical exchange biasing (referring to that external magnetic field is all perpendicular to face in the cold-peace measuring process) to improve the perpendicular magnetic anisotropy of vertical film.Although people also do not attempt utilizing the exchange biased face inner membrance that makes to become vertical film, this work may will have very important significance to the high density information field of storage.
Perpendicular magnetic anisotropy is one of necessary condition of high-density magneto-optical storage and high-density perpendicular magnetic recording medium.Produce perpendicular magnetic anisotropy in the past following several method is arranged: (1) some heavy rare earth metal alloy firms present, as Gd-Fe, and Tb-Fe-Co etc.; (2) Co-Pt, Fe-Pt, Co-Pd, Fe-Pd etc. are that the alloy firm of base also has perpendicular magnetic anisotropy with Pd and Pt; (3) utilize shape anisotropy in magnetic recording media, to realize perpendicular magnetic anisotropy; (4) the another kind of method that produces perpendicular magnetic anisotropy is the interface anisotropy of utilizing in magnetic/non magnetic multilayer film.Above-mentioned the whole bag of tricks all has a common defective, has only some specific element combinations could realize perpendicular magnetic anisotropy, and significant limitation is arranged.
Because perpendicular magnetic anisotropy is the necessary condition that realizes high-density perpendicular magnetic recording and magneto-optic storage, therefore seek the new method that realizes the perpendicular magnetic anisotropy in the magnetoresistance effect, to have important potential using value at high-density perpendicular magnetic recording and magneto-optic field of storage, help to promote the development of high-tech areas such as information stores, and might produce huge economic benefits.
Summary of the invention
The objective of the invention is to propose a kind ofly can in magnetoresistance effect, realize the method for perpendicular magnetic anisotropy, and overcome above-mentioned existing methods defective.
The method that realizes perpendicular magnetic anisotropy in the magnetoresistance effect that the present invention proposes is to utilize the vertical exchange biasing in ferromagnetic/antiferromagnetic multilayer film to realize perpendicular magnetic anisotropy, and concrete steps are as follows:
1, on substrates such as glass or silicon, with the vacuum coating method alternating deposit ferromagnetic/inverse ferric magnetosphere constitutes the modulated structure multilayer film, the cycle of rete is 5-100, the thickness of ferromagnetic layer is the 0.1--10 nanometer, inverse ferric magnetosphere thickness is that the 1-99 nanometer does not wait.
2, on multilayer film, cover one deck anti oxidation layer again, so that multilayer film is protected.This anti-oxidation protection layer material can be Cu, SiO
2, Au, Ta etc.
3, then the multilayer film sample is carried out the magnetic field cooling, wherein the direction of external magnetic field is parallel to the normal direction of face, drop to the N that is lower than inverse ferric magnetosphere from the N that is higher than inverse ferric magnetosphere, externally-applied magnetic field needs enough big, makes that the magnetization of ferromagnetic layer can be along the normal direction saturation magnetization.
Before the deposit multilayer film, deposition one layer thickness is the resilient coating of 1--99 nanometer earlier on substrates such as glass or silicon.This cushioning layer material can be various materials, as long as it is exchange biased to make inverse ferric magnetosphere to realize.
Among the present invention, ferromagnetic layer can be Fe, Co, Ni, rare earth metal and alloy thereof, and inverse ferric magnetosphere can be variously can have exchange biased antiferromagnet; Cushioning layer material can be Cu, Ta, Cr etc., and the selection of resilient coating is mainly decided according to anti-magnetosphere material.Vacuum coating method can be common magnetically controlled sputter method etc.
The vertical exchange biasing of the present invention utilizes ferromagnetic/antiferromagnetic multilayer film, make face inner membrance originally become vertical film, it is fit to all ferromagnetic/antiferromagnetic systems, be suitable for all ferrimagnets, has very large selectivity, can remedy deficiency and defective on the previous methods, so this invention there have been essential difference and qualitative leap.This will have great potential using value to area information storages such as high-density perpendicular magnetic recording and magneto-optic storages.
Description of drawings
Fig. 1, [Fe has been described
19Ni
81(2.0nm)/CoO (4.0nm)]
40Multilayer film is through the magnetic hysteresis loop of cooling back, magnetic field in low temperature and room temperature.
Fig. 2, [Fe has been described
19Ni
81(2.0nm)/CoO (4.0nm)]
40Multilayer film changes along with variation of temperature through cooling back, magnetic field coercive force.
Fig. 3, [Fe has been described
19Ni
81(2.0nm)/Fe
50Mn
50(4.0nm)]
40Multilayer film is through the magnetic hysteresis loop of cooling back, magnetic field under different temperatures.
Embodiment
The invention is further illustrated by the following examples.
Embodiment 1, Fe
19Ni
81/ CoO multilayer film
The magnet layer adopts Fe, Ni alloy Fe
19Ni
81, anti-magnet layer adopts the CoO material, and cushioning layer material adopts Cu, and backing material adopts the Si sheet, and anti oxidation layer adopts the Cu material, and the multifunctional magnetic control sputtering equipment that computerizeds control prepares Fe
19Ni
81/ CoO, wherein Fe
19Ni
81Layer thickness is 2.0nm, and the CoO layer thickness is 4.0nm, and periodicity is 40, and buffer layer thickness is 30.0nm.The concrete structure of sample is Si/Cu (30nm)/[Fe
19Ni
81/ CoO]
40/ Fe
19Ni
81/ Cu (30.0nm).The multilayer film sample is placed in the outfield, and temperature drops to low temperature from room temperature, and to carry out the field cold, and the size in its centre field is 790kA/m, and direction is parallel to the normal direction of face.With superconducting quantum interference device (SQUID) measuring vertical in the magnetic hysteresis loop of face.Shown in figure (1), the magnetic hysteresis loop of sample vertical direction is very oblique during room temperature, and remanence ratio is zero.This shows that sample is the face inner membrance when room temperature.When low temperature, great changes have taken place in the magnetic hysteresis loop of vertical direction, and the remanence ratio of magnetic hysteresis loop and coercive force all constantly increase.This perpendicular magnetic anisotropy that shows multilayer film can constantly increase, very near vertical film.Figure (2) has provided Fe
19Ni
81(2.0nm)/coercive force of CoO (4.0nm) multilayer film vertical direction under different temperatures increases along with the reduction of temperature.This explanation is at Fe
19Ni
81(2.0nm)/CoO (4.0nm) multilayer film in the magnetic field cooling of vertical direction caused perpendicular magnetic anisotropy.
Embodiment 2, Fe
19Ni
81(2.0nm)/Fe
50Mn
50(3.0nm) multilayer film
The magnet layer material adopts Fe, Ni alloy Fe
19Ni
81, anti-magnet layer material adopts Fe, Mn alloy Fe
50Mn
50, resilient coating adopts Cu, and substrate adopts the Si sheet, and anti oxidation layer adopts Cu.The multifunctional magnetic control sputtering equipment that computerizeds control prepares Fe
19Ni
81/ Fe
50Mn
50Multilayer film, wherein Fe
19Ni
81Layer thickness is 2.0nm, and the FeMn layer thickness is 4.0nm, and periodicity is 40, and buffer layer thickness is 30.0nm.The concrete structure of sample is Si/Cu (30nm)/[Fe
19Ni
81/ Fe
50Mn
50]
40/ Fe
19Ni
81(2.0nm)/Cu (30.0nm).With Fe
19Ni
81/ Fe
50Mn
50The multilayer film sample is placed in the outfield temperature and drops to low temperature from room temperature to carry out the field cold, and the size in outfield is 790kA/m, and direction is parallel to the normal direction of face.With superconducting quantum interference device (SQUID) measuring vertical in the magnetic hysteresis loop of face.Figure (3) provides Fe respectively
19Ni
81(2.0nm)/Fe
50Mn
50(3.0nm) magnetic hysteresis loop of multilayer film vertical direction under different temperatures.The remanence ratio of vertical direction and coercive force strengthen with the reduction of temperature.This explanation is at Fe
19Ni
81(2.0nm)/Fe
50Mn
50(4.0nm) cooling of the magnetic field of vertical direction has caused perpendicular magnetic anisotropy in the multilayer film.Illustrate that perpendicular magnetic anisotropy derives from the vertical exchange biasing.