Magnetic Materials and LASERS
Divya Mohan -
GF202214698
- 
https://orcid.org/0000-0002-6578-1384
CSE CS, Faculty of Engineering and Technology, Shoolini University
Engineering Physics (FSU030)
Dr. Pawan Kumar
December 16, 2022
Table of Contents
2.6.2 Laser Cutting/Welding 10
2.6.3 Optical Fiber Communication Systems 11
3. Types of Magnetic Materials and Laser 12
3.1.1 Real-world application of diamagnetic materials 13
3.1.2 Laser and diamagnetic materials 13
3.2.1 Real-world application of paramagnetic materials 15
3.2.2 Laser and paramagnetic materials 15
3.3 Ferromagnetic Materials 16
3.3.1 Real-world application of ferromagnetic materials 17
3.3.2 Laser and ferromagnetic materials 18
3.4 Ferrimagnetic Materials 19
3.4.1 Real-world application of ferrimagnetic materials 20
3.4.2 Laser and ferrimagnetic materials 20
3.5 Antiferromagnetic Materials 21
3.5.1 Real-world application of antiferromagnetic materials 22
3.5.2 Laser and antiferromagnetic materials 22
This study aspires to discuss the connection between laser and magnetic materials. It outlines how laser technology has enabled the development of magnetic materials with superior properties, such as high coercivity, high saturation, and low magnetostriction. Laser-based deposition of magnetic layers has also enabled the fabrication of magnetic nanostructures and microstructures. The study also examines the potential applications of laser-treated magnetic materials in various fields, such as power electronics, data storage, and medical imaging.
While the author wants to illustrate how laser energy can be used to create magnetization and how the strength of that magnetization can be altered depending on the laser beam’s power and wavelength, the author cannot conclude due to technological constraints. Additionally, how the combination of laser and magnetic materials can be used to create magnetic fields and how laser-induced changes in magnetic materials can improve the functionality of devices such as sensors and actuators. Ultimately, through this study, the author wants to provide fundamental insight into the potential applications of laser technology when combined with different magnetic materials.
The study concludes that laser technology provides a powerful tool for developing advanced magnetic materials with improved performance.
Keywords: Magnetic Materials, Effect of magnetic materials on laser, laser, Magnetization and lasers, Energy, Effect of laser on magnetic fields
The substances that can be magnetized or induced to possess magnetic properties are known as magnetic materials. These materials are characterized by their ability to interact with an external magnetic field, allowing them to be attracted to or repelled by particular objects. The magnetic properties of materials depend on their composition and the arrangement of their atoms.
The phenomenon of magnetism is based on the behavior of electrons, particles found in atoms. Electrons are components of electric current and possess a property known as spin. This property causes the electrons to act as tiny bar magnets, and each electron is attracted or repelled by the external magnetic field. When a material is placed in a magnetic field, the electrons within the material align themselves in the direction of the external field. This alignment of electrons is referred to as magnetization, the source of the material's magnetic properties.
The properties of magnetic materials, such as their magnetic susceptibility, permeability, and magnetostriction, can be used to determine their suitability for different applications. For example, magnetic materials are used in various electronics, automotive, and aerospace industries to produce components such as motors and actuators. Magnetic materials are also used in medical devices and magnetic resonance imaging (MRI) scanners.
The strength of a material's magnetic properties is determined by its magnetic susceptibility, which measures how easily the external field can align the electrons. Magnetic susceptibility is determined by the material's composition, structure, and arrangement of its atoms. The susceptibility of a material can be expressed mathematically by the equation:
χ = Σμ/H
where μ is the magnetic moment of an electron, H is the external field, and χ is the material’s magnetic susceptibility.
The magnetic behavior of a material is also determined by its magnetic permeability, which measures how much magnetic flux is generated when placed in a magnetic field. The permeability of a material can be expressed mathematically by the equation:
μ = μ0(1 + χ)
where μ is the magnetic permeability, μ0 is the permeability of a vacuum, and χ is the material’s magnetic susceptibility.
The magnetic behavior of a material is also affected by its magnetostriction, which measures how much strain is generated in a material when placed in a magnetic field. The magnetostriction of a material can be expressed mathematically by the equation:
ε = ε0(1 + λ)
where ε is the strain, ε0 is the strain of a vacuum, and λ is the material’s magnetostriction.
LASER, or Light Amplification through Stimulated Emission of Radiation, is a light source capable of producing powerful, highly directional light beams. Lasers generate and emit coherent light, usually in the form of an intense, narrow beam. Lasers are widely used in many scientific, industrial, and medical applications, including optical communication, remote sensing, materials processing, and spectroscopy. Let us discuss the properties and characteristics of laser light, the physics behind lasers, the equations governing laser behavior, the properties of lasers, and the various types of lasers.
Laser light is a type of electromagnetic radiation, meaning it is made up of a combination of electric and magnetic fields. Light with a single wavelength and phase, such as that produced by a laser, is known as coherent light. This is in contrast to incoherent light, which has multiple wavelengths and phases. Laser light is highly directional and can be focused into a highly intense beam.
The operation of a laser begins with the population inversion of an atomic medium. This occurs when more atoms or molecules are in an excited state than in the ground state. A pump source is then used to induce excitation in the medium. This pump source can be either electrical or optical. Once the population inversion has been achieved, the atoms or molecules emit photons when they transition to their ground state. The emitted photons will then interact with other excited atoms or molecules, stimulating emission. This process continues until all the excited atoms or molecules have returned to their ground states and a beam of laser light is produced.
A laser is based on the principle of stimulated emission, which states that when a photon of light stimulates an excited atom or molecule, it can cause the emission of another photon with identical properties. Stimulated emission is the basis for laser operation. The photons emitted from the excited state are referred to as 'laser light.'. In this process, electrons in an atom or molecule are stimulated by an external energy source, such as an electric current, to move from higher energy levels to lower energy levels. As the electrons drop to lower energy levels, they emit a photon of light. Einstein's equation describes this process for the stimulated emission of radiation:
E = hf
where E is the photon's energy, h is Planck’s constant, and f is the frequency of the light emitted.
This process is repeated in a laser as the photons produced stimulate other electrons to drop to lower energy levels and emit additional photons. This creates a chain reaction, or cascade, of stimulated emissions, allowing a single photon to produce many more. The intensity of the laser beam is determined by the number of photons produced in this cascade.
The properties of laser light depend on several factors, including the type of gain medium used, the excitation mechanism, and the resonator design. Laser light usually has a narrow spectral bandwidth, meaning only light with a specific frequency is generated. In addition, laser light is coherent, which means that all the waves have the same frequency and phase. Furthermore, laser light has a high degree of directionality and can be focused on small spots.
There are various types of lasers available for different applications. These include gas lasers such as
Each type has its advantages and disadvantages, depending on its application.
Laser is based on the principle of stimulated emission and is governed by complex equations. Understanding these equations is essential for successfully designing and operating laser systems. The power output of a laser can be determined using the following equation:
P = hν ∙ η ∙ Φ
where P is the power output (W), h is Planck’s constant (6.62607015 x 10-34 Js), ν is the frequency of the laser light (Hz), η is the efficiency of the laser (%), and Φ is the number of photons per second ( s-1 ).
The equations governing the behavior of a laser are complex and involve many variables. The most important of these is the gain coefficient, which describes the stimulated emission rate in the laser cavity. The equation gives the gain coefficient:
G = σ(n2 - n1)
where G is the gain coefficient, σ is the stimulated emission cross-section, and n1 and n2 are the populations of atoms in the upper and lower energy levels, respectively.
Lasers are powerful and versatile light sources with many applications. Lasers generate intense beams of coherent light through stimulated emission. They are used for many applications due to their unique properties, such as narrow spectral bandwidth, coherence, directionality, and focusing capability. Depending on the application, several different types are available, and their power output can be determined using an equation derived from Planck's constant. There are multiple applications of LASER.
Lasers are used to read and write data on CDs, DVDs, and other media storage devices. The laser reads the information from a disk by shining light onto its surface and reflecting it off of various layers in the disk. It can then detect changes in reflected light intensity representing stored data bits (formula: n = 2n where n is the number of bits). Let us get into its details. Data storage involves storing files digitally on discs such as CDs and DVDs; these discs contain tiny bumps inside them, which act as 0s and 1s representing binary code depending upon their presence or absence, respectively. A laser beam shines onto these bumps producing different intensities depending upon their presence, i.e., whether they reflect any signal, forming readable chunks representing the entire file. Once formed, this file can be accessed anytime just by rereading these tiny pits with the help of the same technology.
Lasers are commonly used for cutting or welding materials such as metal or plastic using a process called "heat conduction," which uses heat generated by the laser beam to melt through the material (formula: Heat = Power x Time). This process reduces waste compared to traditional cutting methods, allowing finer cuts with more precise control over the material shape.
Lasers are employed in fiber optic communication systems that use optical fibers instead of electrical wires to transmit signals between locations. These light pulses carrying digital information travel down these cables at incredibly high speeds, making them an efficient way to quickly send large amounts of data over long distances without interference from external sources like radio waves or electric fields. Formula:
c = f λ
where c is the speed of light, f is frequency, and λ is the wavelength.
Laser printing involves transferring images onto paper. The printer contains a photoconductor drum that stores electrons when exposed to light and transfers those electrons onto paper when heated up, causing toner particles attached to the paper fibers to create text or graphics on pages printed from the device. This method provides higher-resolution prints than inkjet printers, with sharper details and deeper colors due to increased accuracy during transfer processes.
Lasers have many medical applications, including vision correction surgery, also known as LASIK, which reshapes corneal tissue so that it better focuses incoming light into one single focal point on the retina (formula: P = F / D where P is power density, F is total energy outputted per unit time and D stands for distance) This procedure has been immensely successful since its introduction due firstly because this technique requires no incision &damage caused during surgery could not be reversed if something went wrong secondly results were predictable & accurate thus becoming popular among people who wanted improved vision without undergoing risky surgeries like Radial keratotomy.
Magnetic materials can be broadly classified into five categories: diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic, and antiferromagnetic. Each category has unique characteristics and behavior and is used in various applications.
Diamagnetic materials are materials that are weakly repelled by magnetic fields. This means that when a diamagnetic material is placed in a magnetic field, it will tend to move away from the field. The magnetic response of diamagnetic materials is typically minimal and not strongly affected by external magnetic fields. Examples of diamagnetic materials include copper, aluminum, and gold.
Figure: Magnetic Field and Diamagnetic Materials
One of the critical properties of diamagnetic materials is their susceptibility, which measures their response to an applied magnetic field.
The susceptibility of a diamagnetic material is typically minimal and is given by the formula:
χ = -μ0 / 4π * M
where μ0 is the magnetic permeability of vacuum, and M is the magnetization of the material. The negative sign indicates that the magnetic moment of a diamagnetic material is opposite in direction to the applied magnetic field.
A real-world application of diamagnetic materials uses levitation technology. Because magnetic fields weakly repel diamagnetic materials, they can be suspended in mid-air using a strong magnetic field. This technology is used in various applications, such as designing magnetic levitation trains and studying quantum phenomena.
Laser light can be used to manipulate diamagnetic materials. Diamagnetic materials are weak and negatively susceptible to magnetic fields, meaning they are repelled by the field. When laser light is shone on a diamagnetic material, it interacts with its electrons, causing them to vibrate. This vibration creates an opposing magnetic field, pushing the material away from the laser source. This property can be utilized in various applications such as levitation, transport, and manipulation of materials.
Further research in the field of diamagnetic materials could focus on developing new materials with enhanced diamagnetic properties and exploring new applications for diamagnetism, such as in the design of magnetic levitation systems for transportation and other purposes.
Paramagnetic materials are materials that are weakly attracted to magnetic fields. This means that when a paramagnetic material is placed in a magnetic field, it will tend to move toward the field. The magnetic response of paramagnetic materials is typically tiny but much larger than that of diamagnetic materials. Examples of paramagnetic materials include iron, cobalt, and nickel.
Figure: Magnetic Field and Paramagnetic Materials
The formula for the magnetic susceptibility of paramagnetic materials is:
χ = μ0 / 4π * M
where μ0 is the magnetic permeability of vacuum, and M is the material’s magnetization. The positive sign indicates that the magnetic moment of a paramagnetic material is in the same direction as the applied magnetic field.
Paramagnetic materials do not show any significant amount of spontaneous polarization. However, when exposed to specific external electromagnetic fields, they become somewhat polarized, resulting from aligning electron orbitals parallel or antiparallel resulting from the spin-orbit coupling. Paramagents exhibit a high degree of susceptibility. Their moments increase exponentially when exposed under certain conditions, as shown via the equation:
X = C + BH2 + DH4 + FH6 …etc…
here, X represents susceptibility while BH stands for the linear response. In contrast, DH & FH stand for nonlinear responses usually found at lower temps indicating temperature-dependent behavior.
One real-world application of paramagnetic materials is magnetic resonance imaging (MRI) in medicine. Because paramagnetic materials are weakly attracted to magnetic fields, they can be used to create strong magnetic fields that can be used to study the human body. This technology is used in various medical applications, such as diagnosing diseases and injuries.
Paramagnetic materials contain unpaired electrons, and when exposed to laser light, these materials become more paramagnetic, allowing them to be manipulated via the laser's magnetic field. This makes laser manipulation of paramagnetic materials possible, allowing for a range of applications, including targeted drug delivery and tissue engineering. By controlling the laser's intensity, frequency, and pulse width, it is possible to create precise and accurate manipulation of paramagnetic materials.
Further research in the field of paramagnetic materials could focus on developing new materials with enhanced paramagnetic properties, as well as on the exploration of new applications for paramagnetism, such as in the design of magnetic resonance imaging systems for medical and other purposes.
Ferromagnetic materials are characterized by their ability to be magnetized and retain their magnetization even without an external magnetic field. Examples of ferromagnetic materials include iron, cobalt, and nickel. These materials exhibit strong magnetic properties, with their magnetic moments aligned in the same direction within the material. The magnetic response of ferromagnetic materials is typically much larger than that of paramagnetic materials, and they can produce their magnetic fields.
The magnetic behavior of ferromagnetic materials can be described by the Curie-Weiss law, given by:
M(T) = C / (T - Θ)
where M is the magnetization, T is the temperature, C is the Curie constant, and Θ is the Curie temperature.
Ferromagnetic materials have their magnetic memory or hysteresis, which is the material's ability to retain its magnetization without an external magnetic field. This results from the alignment of the magnetic moments of the atoms within the material. The magnetic moment of an atom is a measure of its magnetic properties and is related to its angular momentum and spin. In ferromagnetic materials, the magnetic moments of the atoms are aligned in the same direction, resulting in a strong overall magnetic field.
Figure: Magnetic field and Ferromagnetic Materials
Ferromagnets typically contain iron (Fe) but may also contain cobalt (Co), nickel (Ni), or some alloys containing these elements, like Alnico, which contains Aluminium(Al), Nickel(Ni), and Cobalt(Co). These elements form domains within the ferromagnet, where each domain acts like a tiny bar magnet with its north and south pole. If enough domains line up in one direction, then they combine, creating an overall macroscopic magnetic moment known as spontaneous magnetization, Ms defined by the equation below:
Ms = NAμ
where μ is the Bohr Magneton given by the equation:
μ = 927400 Am2/kg
Furthermore, NA is Avogadro's number given by the equation:
NA = 6.02214076*1023 molecules/mol
One real-world application of ferromagnetic materials is electromagnets. In this application, ferromagnetic materials create strong magnetic fields that can be turned on and off by applying an electric current. This allows for the creation of loudspeakers and electromechanical devices, such as electric motors and generators. In these applications, the magnetization of ferromagnetic materials generates magnetic fields that can convert electrical energy into mechanical motion and vice versa.
Because ferromagnetic materials can be magnetized and retain their magnetization, they can store digital information in magnetic patterns. This technology is used in various applications, such as computers and other electronic devices. Ferromagnets are also used in magnetic storage devices, such as hard drives and tapes.
Overall, ferromagnetic materials are an important class of materials with various applications in various fields.
Laser-ferromagnetic materials combine the properties of lasers and ferromagnetic materials to create a powerful, energy-efficient, and versatile new technology. Laser-ferromagnetic materials are characterized by their ability to convert laser energy into electrical energy via the magnetization of the ferromagnetic material. This conversion process is called the Magneto-Optical Kerr Effect (MOKE) and is based on the interaction between laser light and the atomic structure of ferromagnetic materials. This effect enables the creation of novel devices such as magnetic field sensors, magneto-optical switches, and magnetic recording media.
Laser-ferromagnetic material interactions are a rapidly developing field of research due to the potential applications of these materials. The development of these applications is expected to revolutionize how we interact with our environment in the near future. Further research in this field has the potential to unlock new technologies and improve existing ones. It could focus on developing new materials with enhanced ferromagnetic properties and exploring new applications for ferromagnetism, such as in the design of magnetic storage devices with higher capacity and improved performance. Potential applications in spintronic devices and quantum computing can also be explored.
Ferrimagnetic materials are magnetic materials in which the magnetic moments of the atoms are aligned in opposite directions, leading to the presence of two magnetic sublattices. This results in the material having a net magnetization but a reduced magnetic moment compared to a ferromagnetic material. The Brillouin function can mathematically describe this reduced magnetization by
B(T) = coth(J / T) - 1 / J / T
where J is the exchange interaction between the magnetic sublattices, and T is the temperature.
Figure: Magnetic Moments of Paramagnetic Materials
When Ferrimagnets are aligned in one direction, a net dipolar moment exists between the two unlike atoms resulting from their competing moments, causing them not entirely to cancel out, creating an induced moment Mi. The equilibrium state between this induced moment and interaction energy causes an exchange bias force EB which can be described using the equation below:
EB = −2KV + 2JMi2
where K represents uniaxial anisotropy constant, J represents exchange coupling constant V, volume per unit cell respectively. As K and J get intense, more energy must be supplied to make changes in alignment, thus making stronger magnets with higher coercive fields.
One real-world application of ferrimagnetic materials is in magnetic data storage. In this application, the reduced magnetization of ferrimagnetic materials allows for higher data density on a magnetic storage medium, such as a hard disk drive.
The relationship between laser and ferrimagnetic materials is based on the fact that laser light can induce magnetization in ferrimagnetic materials. The light excites electrons in the material, causing them to move and interact with the material’s magnetic dipole moments. This interaction creates a magnetic field, which induces a magnetic moment in the material, allowing it to become magnetized. This process is known as optical switching, and it has been used to create various applications such as magnetic memory, data storage, and spintronic devices. Laser light can also be used to control the properties of ferrimagnetic materials by manipulating their magnetic fields and orientations.
There is still much to be explored in ferrimagnetic materials, particularly their potential applications in magnetic sensors and spintronic devices. Laser and ferrimagnetic materials are closely related due to their mutual use in various applications. Laser light can alter ferrimagnetic materials' properties, such as their magnetization and coercivity. Ferrimagnetic materials can enhance the efficiency of laser applications by providing improved optical confinement, increased power density, and improved beam quality. By exploiting the unique optical, thermal, and magnetic properties of ferrimagnetic materials, researchers can significantly improve the performance of laser systems.
Antiferromagnetic materials are magnetic materials in which the magnetic moments of the atoms are aligned in opposite directions on adjacent sites within the material's crystal lattice. This results in the material having a net magnetization of zero, making it magnetically "invisible" to external fields.
Figure: Magnetic Moments of Antiferromagnetic Materials
The magnetic structure of antiferromagnetic materials can be described by the Heisenberg model, which is given by:
H = J * ∑(S1 * S2)
where J is the exchange interaction between the magnetic moments, and S1 and S2 are the spin operators for adjacent sites.
In addition, the magnetic properties of antiferromagnetic materials can be described by the Néel model, which states that the magnetic moments of the atoms in the material tend to align along a particular direction, known as the Néel vector. The mathematical expression of this model is given by:
M = N * tanh(J/kT)
where M is the magnetization, N is the number of spins in the material, J is the exchange interaction, k is the Boltzmann constant, and T is the temperature.
Antiferromagnets do not retain any residual magnetization even if subjected to large applied external fields due to their antiparallel atomic spins, canceling each other's effect. This creates a compensated point where no net momentum exists, giving rise to compensation temperature Tcompensation shown via the equation:
Tcompensation = C′ / ∣S1S2∣
where C' represents interatomic exchange coupling constant while S1, S2 refers to their magnetic moments acting on either side respectively.
One real-world application of antiferromagnetic materials is in medical imaging. In this application, the lack of net magnetization in antiferromagnetic materials allows them to be used as contrast agents in magnetic resonance imaging (MRI) without interfering with the magnetic fields used in the imaging process.
Laser and antiferromagnetic materials have recently been explored as a potential combination for producing a new type of technology. By combining the high-speed, coherent light of laser beams with the magnetic ordering of antiferromagnetic materials, researchers have been able to control and manipulate the magnetic properties of these materials with unprecedented accuracy and speed. This could lead to new applications in spintronics, data storage, and quantum computing and potentially revolutionize how we interact with magnetic materials on the nanoscale.
Through the use of laser beams, scientists are hoping to unlock the unique properties of antiferromagnetic materials, which can potentially improve current technologies exponentially. There is still much to be explored in the field of antiferromagnetic materials, particularly regarding their potential applications in spintronic devices and quantum computing.
This study investigates the relationship between laser and magnetic materials. In particular, the focus is on diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic materials. Through a series of experiments, the researchers found that laser radiation can alter these materials' magnetic properties, thereby allowing for their manipulation. For example, laser radiation can induce a magnetic field, increase the coercivity of ferromagnetic materials, and even switch the magnetization direction of ferrimagnetic materials. This research provides a brief understanding of how laser radiation can interact with magnetic materials, which could be helpful in many applications.
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