Nanoscale Magnetic Materials And Devices Engineering Essay

Introduction:

At present analyzing the belongingss of Nano-elements and Nano-structures have outstanding involvement among the research workers and scientists. Analyzing the Nano-scale magnetic stuffs is under the development for planing the widest Nano-scale devices and doing the devices ready for the existent universe. This study is presented in three parts where in the first portion we are traveling to look into the micro-magnetic belongingss of the thin Nano-element Permalloy and in the 2nd portion Fe is investigated utilizing the two-dimensional version of OOMMF from NIST by altering different parametric quantities of the stuffs such as cell size, form and magnetization angles and an elaborate analysis is provided sing the alteration in sphere construction. In the 3rd portion we investigate the Permalloy by altering one of the parametric quantities viz. exchange energy and execute the simulations utilizing two-dimensional constructions and the form considered for the soft magnetic Permalloy is egg-shaped form. We besides investigate the effects on the egg-shaped shaped Permalloy on altering the stuff parametric quantity exchange energy.

Problem 1:

The stuff investigated in this job is a soft Ferro magnetic stuff known as Permalloy. Permalloy is a complex of 80 % Ni and 20 % Fe and it has low magneto limitation and has high magnetic permeableness.

Using 2D version of OOMMF we are look intoing the micro magnetic construction of Permalloy. Assorted surveies and observations were made by changing the parametric quantities like form ‘s ( altering the breadth and thickness ) and besides by altering the different initial magnetisation angles which can be observed below.

The method used here to look into the belongingss of Permalloy is two dimensional version of OOMMF. OOMMF is an abbreviation of Object Oriented Micro Magnetic Frame Work. Don porter is one of the chief subscribers for this OOMMF. In order to analyze the belongingss and behavior of the Permalloy we must see the parametric quantities as shown in the tabular array below before executing the simulation.

Parameter

Permalloy

Magnetic impregnation ( Ms ) ( A/m )

860E3

Exchange energy ( A ) ( J/m )

13E-12

Anistropic energy ( K1 ) ( J/m )

0

Muffling Coeffiencent ( moist coeff )

0.5

We study the part-geometry for the given sample i.e. Permalloy in order to detect the assorted alterations in the belongingss of the sample when the form is altered.

In the below survey performed we consider the square sample as the landmark for the other surveies taken under consideration. We make alterations in the highs of the sample ( 60, 80,120,140 ) and we study their belongingss separately and so comparing them all. In the sample considered here, merely the alterations are made in the forms of the Permalloy and rest all the parametric quantities such as cell size, thickness etc are kept changeless. Another survey has been besides performed for the sample by altering the initial magnetisation angles N? and N„ . We have taken assorted initial magnetisation angles harmonizing to the convenience such as N? =45, N„=45 and N? =90, N„=90 and N? =135, N„=135 so N? =175, N„=175.

Study1:

In this instance we consider the square sample of Permalloy with a thickness of 4nm and the other parametric quantities considered can be seen in the tabular array below:

Width ( m )

40e-9

Height ( m )

40e-9

Thickness ( m )

4e-9

Cell-Size ( m )

5e-9

Consequences:

a ) For Permalloy of width-40nm, height-40nm, Thickness-4nm and cell size-5nm

Observation1:

The dipole turns towards the easy axis when a field is applied which would be the longer axis of the form considered. In a square the diagonal is the longer axis and therefore the dipoles align diagonally when a field is applied to it.

The dipole faces the longer axis in order to cut down the magnetisation energy.

Zeeman Effect is zero because no electric field is applied to the sample.

Anisotropy energy is besides nothing because the sample ( Permalloy ) is uniaxial.

Since all the dipoles are aligned in same way the exchange energy dominates the demagnetisation energy for the sample.

The dipoles are parallel to shave and the Neel-walls are formed due to the thickness of the sample i.e. 4nm.

Survey 2: –

For Permalloy with width-40nm, height-60nm, thickness-4nm and cell size-5nm

Observation 2:

Now the longer axis is along the tallness instead than the diagonal since the form have been changed from a square to a rectangle, the dipoles aligned along the longer axis.

Zeeman Effect is zero because no electric field is applied ; Anisotropy energy is besides zero due to the uniaxial belongings of Permalloy and as all dipoles is aligned towards the longer axis in order to cut down the demagnetisation energy.

The exchange energy besides dominates here since the dipoles are aligned in same way.

We can detect from the figure that the dipoles are non wholly aligned directly along the length of the rectangle it could be because the dipoles at the border of the samples are alining along the longer axis. And therefore we increase the length of the sample and observer the dipoles.

Survey 3: For the Permalloy with dimensions as width-40nm, height-80nm, thickness-4nm and cellsize-5nm

Observation 3:

The dipoles in the rectangle sample considered here are aligned along the easy axis on application of magnetic field i.e. along the longer side of the length of the rectangle.

Zeeman consequence is zero due to no electric field applied and anisotropy energy is zero as it is uniaxial and exchange energy dominates here due to all dipoles are confronting towards same way that is longer axis.

We can detect dipoles at the borders of the sample that they are still non aligned along the consecutive line.

Survey 4:

For Permalloy with width-40nm, height-140nm, thickness-4nm and cell-size-5nm

Observation 4:

From the above figure we can detect that:

The dipoles are now aligned along the easy axis i.e. the longer axis of the sample and we can besides detect the dipoles are alining directly around the corner or borders of the sample.

Zeeman Effect and anisotropy energy are zero due to as no electric field is applied and due to it is uniaxial. And all dipoles are in same way to diminish the demagnetization energy. Exchange energy dominates here besides.

Survey 5:

Comparison for alteration in breadth or tallness:

For Permalloy with width-40nm, height-40nm.thickness-4nm, cell-size-5nm

For Permalloy with width-140nm, height-40nm, thickness-4nm, cell size-5nm

From the above comparing it is noticed that the simulation done for the concluding consequences show same consequence whether there is addition in breadth or increase in height the dipoles align towards the longer axis. The other belongingss remain the same like exchange energy dominates here because all dipoles align in same way. The belongingss which are seen in the instance of alteration in tallness will stay same for alteration in breadth besides.

Survey 6:

Initial magnetisation angles:

Degree centigrades: UsersUserPicturesUntitled.jpg

No.of samples/simulations

N?

N„

Width ( tungsten )

Height ( H )

Thickness

Cell-Size

a

45A°

45A°

60e-9

40e-9

4e-9

5e-9

B

90A°

90A°

60e-9

40e-9

4e-9

5e-9

degree Celsiuss

135A°

135A°

60e-9

40e-9

4e-9

5e-9

vitamin D

160A°

160A°

60e-9

40e-9

4e-9

5e-9

vitamin E

175A°

175A°

60e-9

40e-9

4e-9

5e-9

Analysis 6:

Comparing and analyzing from the above graphs for the initial magnetisation angle we can detect that the way of dipoles change with the alteration in the initial magnetisation angle although the exchange energy dominates the demagnetisation energy and therefore the dipoles aligned along the same waies. With the alteration in the initial magnetisation angle the dipoles does n’t alter the easy axis belongings on application of magnetic field i.e. the dipoles still aligned along the longer axis way merely.

Problem-2 ( sample 2 Fe ) :

In this job we are look intoing the belongingss of Iron. Iron is the most abundant component found in Earth crust and which can besides be found in the human organic structure in the signifier of hemoglobin which occupy two-third of organic structure.

We use the same package OOMMF for the simulation and to detect the belongingss of Fe. Changing the parametric quantities like cell size and breadth and maintaining other parametric quantities constant we observe the fluctuation in the belongingss of Fe.

First as discussed in OOMMF package the stuff must selected, here it is Fe and the parametric quantities of the stuff will be as shown below tabular array.

Parameter

Iron

Magnetic impregnation ( Ms ) ( A/m )

1700E3

Exchange energy ( A ) ( J/m )

21E-12

Anistropic energy ( K1 ) ( J/m )

48E3

Muffling Coeffiencent ( moist coeff )

0.5

Then the part-geometry of the stuff is selected as given in job and that is given in below in item.

Width

500e-9

Height

200e-9

Thickness

60e-9

Cell-Size

5e-9

Initially the cell size is varied from 2-10nm at an interval of 2, while the other parametric quantities are changeless. Second, the breadth of the sample is varied from 500-50nm at an interval of 50nm and maintaining all other parametric quantities every bit changeless as mentioned above.

a ) Change in cell size:

1 ) For Fe with width-500nm, height-200nm, thickness-60nm, cellsize-2nm

2 ) For Fe with width-500nm, height-200nm, thickness-60nm, cellsize-4nm

3 ) For Fe with width-500nm, height-200nm, thickness-60nm, cellsize-5nm

4 ) For Fe with width-500nm, height-200nm, thickness-60nm, cellsize-10nm

General belongingss of the above samples:

Iron has a three-dimensional crystalline construction and Anisotropy energy is non zero as in the instance of soft magnetic stuff Permalloy because of the three-dimensional crystalline belongings of Fe.

Zeeman Effect is zero because we do n’t use any electric field ; the simulations are done by using the magnetic field.

Here Bloch walls are formed instead than Neel ‘s walls due to the higher thickness of the sample.

The demagnetization energy dominates in the above samples because due to formation of sphere walls.

The entire exchange energy attempts to aline the dipoles in a homogeneous manner but due to the domination of demagnetisation energy the spheres formation takes topographic point.

The net magnetisation at the Centre of the sphere walls formed is zero.

Comparison of above samples in their cell size:

If the cell size is less than 5nm ( up to 2nm ) the spheres walls can be observed with the addition in figure of whirls. If the cell size increased more than 5nm ( up to 10nm ) the sphere walls disappears and the figure of whirls besides decreases. But if the cell size is nearer to 5nm ( between 4 to 5nm ) shows the formation of sphere walls.

The demagnetization energy for the sample holding cell size more than 5nm ( up to 10nm ) dominates exchange energy. But for the cell size nearer to 5nm ( between 4nm to 5nm ) and less than 5nm ( up to 2nm ) shows the domination of demagnetization energy over the exchange energy which is more than the samples holding cell size more than 5nm ( up to 10nm ) .

The demagnetization energy for the sample holding less cell size than 5nnm ( up to 2nm ) and more than 5nm ( up to 10nm ) are relatively low than the cell size near to 5nm ( between 4-5nm )

4 ) The net magnetization formed at the Centre of sphere walls or at the whirl is zero.

B ) Change in breadth of sample:

Uracil: ManXPMy DocumentsMy Pictures3.JPG

Uracil: ManXPMy DocumentsMy Pictures2.JPG

No.of samples/simulations

Width ( W )

Height ( H )

Thickness

Cell-Size

a

500e-9

200e-9

60e-9

5e-9

B

450e-9

200e-9

60e-9

5e-9

degree Celsiuss

400e-9

200e-9

60e-9

5e-9

vitamin D

350e-9

200e-9

60e-9

5e-9

vitamin E

300e-9

200e-9

60e-9

5e-9

degree Fahrenheit

250e-9

200e-9

60e-9

5e-9

g

200e-9

200e-9

60e-9

5e-9

H

150e-9

200e-9

60e-9

5e-9

I

100e-9

200e-9

60e-9

5e-9

J

50e-9

200e-9

60e-9

5e-9

Comparing the above graphs of the Fe sample we observe that as the breadth of the Fe decreases sphere walls are formed and there is alteration in figure of whirls formed. Iron with width 500nm had two whirls were obtained from the simulation. As the breadth goes on diminishing from 450nm to 50nm the alteration in figure of whirls is ascertained. As the form goes form rectangular to square so figure of sphere walls formed is diminishing. For the rectangular form with width 500nm, 450nm, 400nm it is observed that Fe with three-dimensional construction organizing the sphere walls with whirl and the net magnetisation energy at the Centre of the sphere walls is zero. The demagnetization energy is ruling in the instance of Fe. But as the breadth sizes ranges nearer to the square the sphere walls are decreased and the figure of whirls are besides reduced.

So at breadth of 50nm we observe there are three sphere walls so this can be summarised as length increases the figure of sphere walls increases. If the length decreases the figure of sphere walls besides decreases. The demagnetization field for rectangular form is much higher than demagnetization in square form in Fe. Because the demagnetization energy dominates the exchange energy in all instances but for the square and rectangular instances the demagnetization energy for rectangular sample dominates the exchange energy more compared to the demagnetization energy in the square dominates the exchange energy. The anisotropy energy in Fe is non zero because it is three-dimensional crystalline in form and Zeeman consequence is zero since no electric field is applied and merely the magnetic field is applied. The dipoles rotate along domain walls when a magnetic field is applied to the Fe sample to cut down the entire energy. The exchange energy in square form is more than in rectangular form but so besides the demagnetisation energy dominates in both the instances.

Problem-3

In this job we are traveling to look into a simple 2D construction of Permalloy by altering its exchange energy for the same sample of same parametric form and observe whether there is any alteration with the alteration in exchange energy.

We perform the simulation utilizing OOMMF package for Permalloy by altering its exchange energy at different stairss. The parametric values for the sample considered can be observed in below tabular array. Below shown the tabular array for the stuff parametric quantities considered.

Parameter

Custom

Magnetic impregnation ( Ms ) ( A/m )

5e-12

Exchange energy ( A ) ( J/m )

13E-12

Anistropic energy ( K1 ) ( J/m )

0

Muffling Coeffiencent ( moist coeff )

0.5

The following are exchange energies considered for the oval form sample of Permalloy: 5e-12, 10e-12, 50e-12,100e-12,300e-12,500e-12,850e-12, 1000e-12, 1300e-12, and 1500e-12.

And so portion geometry selected for the sample is shown below in the tabular array and the form of spheres considered is ellipse but non a rectangular as above.

Width

40e-9

Height

50e-9

Thickness

4e-9

Cell-Size

5e-9

a ) Change in exchange energy:

1 ) For stuff with exchange energy-5e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

2 ) For stuff with exchange energy-10e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

3 ) For stuff with exchange energy-50e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

4 ) For stuff with exchange energy-100e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

5 ) For stuff with exchange energy-300e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

6 ) For stuff with exchange energy-500e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

7 ) For stuff with exchange energy-850e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

8 ) For stuff with exchange energy-1000e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

9 ) For stuff with exchange energy-1300e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

10 ) For stuff with exchange energy-1500e-12, width-40nm, height-50nm, thickness-4nm and cell size-5nm

The exchange energy dominates in the instance of Permalloy and this is the ground for alining the dipoles in a homogeneous manner. When we are increasing the exchange energy i.e. we are doing the dipoles parallel to each other and since it ‘s an ellipse sample we can non see some of the pointers at borders. The dipoles align in a homogeneous manner ( i.e. in a consecutive manner ) as we decrease the exchange energy these dipoles will non be in parallel manner they will be traveling out instead than in parallel because of the lessening in exchange energy. And the exchange energy is the chief ground for the uniaxial stuffs and any other stuff for alining of dipoles in a consecutive manner although the demagnetisation dominates in some stuff and it consequences in sphere walls. And from graphs we can detect that both exchange energy, anisotropy energy and demagnetization energy are diminishing. We can besides detect that all dipoles at their borders are traveling towards the sphere walls.

We can detect that the dipoles change their way on altering the parametric quantity of the sample it is because of the magnetization. There are really two type of magnetisation ( positive & A ; negative ) . Depending on the applied magnetic field the magnetisation alterations and hence the way of the dipoles.

Decision:

In this study we have investigated the passage between the sphere constructions of a square to a rectangular of a soft magnetic stuff Permalloy. We have observed that the way of dipoles prevarications along the longer axis irrespective of the form. In a square it was the diagonal and in rectangular it was the length. We observe that the maximal length of rectangular at which the dipoles lie along the length was found to be 140 nanometer. The alteration in magnetization construction was observed at 60nm. We besides investigated by altering one of the stuff parametric quantity that is magnetisation angle and it was observed that the way of dipoles alterations with the alteration in initial magnetization angles.

For the 2nd sample Fe we have investigated and explained about the sphere construction nowadays in Fe by changing the cell size from 1nm to 10nm. The effects were simulated utilizing the OOMMF ‘s package and it is reported in the above study. We have significantly decreased the breadth by 50nm from 500nm maintaining the cell size changeless i.e. 5nm.We besides observed and reported the alteration in magnetization construction for the sample Fe.

We have reported about the soft magnetic stuff Permalloy with the egg-shaped form. We have besides investigated the alteration that effects the dipoles by altering the exchange energy for the material Permalloy. It was observed that there was a good dependance of exchange energy on the dipoles as the exchange energy was reduced the demagnetization consequence dominates and which changes the dipole aligned observed from the above simulations and vice-versa.