Slide 1

  • Topic: Diamagnetic Materials
  • Definition: Materials that produce a weak opposing magnetic field when placed in an external magnetic field.
  • Example: Bismuth, Copper, Zinc
  • Characteristics:
    • No unpaired electrons
    • No permanent magnetic moment
    • Repelled by strong magnetic fields
  • Equation: Magnetic field inside diamagnetic materials is given by: $\mathbf{B=\mu_0(H+M)}$

Slide 2

  • Topic: Paramagnetic Materials
  • Definition: Materials that are weakly attracted to an external magnetic field.
  • Example: Aluminum, Platinum, Oxygen
  • Characteristics:
    • Have some unpaired electrons
    • Do not retain magnetism after the external field is removed
    • Get magnetized in the direction of the magnetic field
  • Equation: The magnetic susceptibility of paramagnetic materials is given by: $\chi = \frac{M}{H}$

Slide 3

  • Topic: Ferromagnetic Materials
  • Definition: Materials that can be strongly magnetized in an external magnetic field and retain their magnetism after the field is removed.
  • Example: Iron, Nickel, Cobalt
  • Characteristics:
    • Have a large number of unpaired electrons
    • Exhibit spontaneous magnetization
    • Exhibit hysteresis
    • Can be magnetized and demagnetized easily
  • Equation: Magnetic field inside ferromagnetic materials is given by: $\mathbf{B=\mu_0(H+M)}$

Slide 4

  • Topic: Magnetic Field of the Earth
  • Definition: The magnetic field generated by the Earth due to its core’s magnetism.
  • Properties:
    • Acts similar to a bar magnet
    • Axis of the magnetic field is inclined with respect to the Earth’s rotation axis
    • Earth’s magnetic poles are not aligned with its geographic poles
  • Equation: The magnetic field at a point due to the Earth’s magnetic field is given by: $\mathbf{B=\mu_0(H+M)}$

Slide 5

  • Topic: Diamagnetic Materials (Continued)
  • Applications:
    • Magnetic levitation (Maglev) trains
    • Magnetic resonance imaging (MRI) machines
    • Magnetic separators
  • Use of superconducting magnets to achieve levitation and stability
  • Example: Magnetic levitation of a superconductor

Slide 6

  • Topic: Paramagnetic Materials (Continued)
  • Applications:
    • Magnetic resonance imaging (MRI)
    • Particle accelerators
    • Magnetic storage devices
  • Example: MRI machine and its working principle
  • Equation: Langevin’s Theory of Paramagnetism: $M = \frac{CNB}{T}$

Slide 7

  • Topic: Ferromagnetic Materials (Continued)
  • Applications:
    • Transformers
    • Motors and generators
    • Magnetic hard drives
  • Example: Electric motor working principle
  • Hysteresis loop and magnetic memory in ferromagnetic materials

Slide 8

  • Topic: Magnetic Field of the Earth (Continued)
  • Earth’s magnetic dipole
  • Magnetic declination and inclination
  • Magnetosphere and its role in protecting Earth from the solar wind

Slide 9

  • Topic: Diamagnetic Materials (Continued)
  • Diamagnetic substances repel magnetic fields, but the effect is weak
  • Applications of diamagnetic materials in levitation and materials characterization
  • Example: Diamagnetic levitation of a frog

Slide 10

  • Topic: Paramagnetic Materials (Continued)
  • Paramagnetic materials have a small positive magnetic susceptibility
  • Applications in magnetic separation, chemical analysis, and magnetic resonance imaging (MRI)
  • Examples: Magnetic separation of iron ore, MRI scanning process

Slide 11

  • Topic: Magnetic Field of the Earth (Continued)
  • Geomagnetic field
    • Generated by convection currents in the Earth’s outer core
    • Composed of a dipole component and non-dipole components
  • Magnetic field lines and magnetic flux
  • Gauss’s law in magnetism: $\mathbf{\oint B \cdot dA = 0}$

Slide 12

  • Topic: Diamagnetic Materials (Continued)
  • Magnetic susceptibility of diamagnetic materials: $\chi \approx -1$
  • Meissner effect and superconductivity
  • Diamagnetic shielding and levitation applications
  • Example: Magnetic levitation using a superconductor

Slide 13

  • Topic: Paramagnetic Materials (Continued)
  • Magnetic susceptibility of paramagnetic materials: $\chi > 0$
  • Curie’s law: $M = C \left(\frac{B}{T}\right)$, where $C$ is a constant
  • Paramagnetic behavior of atoms and free electrons
  • Applications of paramagnetic materials in chemical analysis

Slide 14

  • Topic: Ferromagnetic Materials (Continued)
  • Magnetic domains and domain walls
  • Weiss theory and the existence of permanent magnets
  • Ferromagnetic resonance (FMR) and spin waves
  • Magnetic anisotropy and magnetic memory

Slide 15

  • Topic: Magnetic Field of the Earth (Continued)
  • Magnetic pole reversals and paleomagnetism
  • Study of past magnetic field through rocks and sediments
  • Secular variation and geomagnetic jerks
  • International Geomagnetic Reference Field (IGRF) model

Slide 16

  • Topic: Diamagnetic Materials (Continued)
  • Examples: Diamagnetic properties of water, graphite, and copper
  • Theory of diamagnetism based on Lenz’s law
  • Measuring diamagnetic susceptibility using Gouy method
  • Comparison of diamagnetism with other magnetic behaviors

Slide 17

  • Topic: Paramagnetic Materials (Continued)
  • Examples: Paramagnetic properties of oxygen, aluminum, and platinum
  • Effect of temperature on paramagnetism
  • Brillouin’s law and magnetic susceptibility of paramagnetic ions
  • Magnetic susceptibility of free electrons in metals

Slide 18

  • Topic: Ferromagnetic Materials (Continued)
  • Examples: Ferromagnetic properties of iron, nickel, and cobalt
  • Saturation magnetization and spontaneous magnetization
  • Exchange interaction and magnetic ordering
  • Magnetic domains and their behavior under external magnetic field

Slide 19

  • Topic: Magnetic Field of the Earth (Continued)
  • Origin of the Earth’s magnetic field
  • Dynamo theory and the role of convection currents in the outer core
  • Geomagnetic storms and auroras
  • Impact of the Earth’s magnetic field on navigation and communication

Slide 20

  • Topic: Diamagnetic Materials (Continued)
  • Industrial applications of diamagnetic materials
  • Magnetic properties of superconductors at low temperatures
  • Superconducting levitation and its potential applications
  • Example: Magnetic levitation of a superconducting train

Slide 21

  • Diamagnetic, Paramagnetic And Ferromagnetic Materials, Magnetic Field Of The Earth - Diamagnetic, Paramagnetic And Ferromagnetic Materials, Magnetic Field Of The Earth – An introduction

Slide 22

  • Diamagnetic Materials
    • Weak opposing magnetic field
    • No unpaired electrons
    • No permanent magnetic moment
    • Repelled by strong magnetic fields
    • Equation: $\mathbf{B=\mu_0(H+M)}$

Slide 23

  • Paramagnetic Materials
    • Weakly attracted to an external magnetic field
    • Some unpaired electrons
    • No magnetism after field removal
    • Get magnetized in the direction of the magnetic field
    • Equation: $\chi = \frac{M}{H}$

Slide 24

  • Ferromagnetic Materials
    • Strongly magnetized in an external magnetic field
    • Retain magnetism after field removal
    • Large number of unpaired electrons
    • Exhibit spontaneous magnetization
    • Hysteresis and easy magnetization/demagnetization

Slide 25

  • Magnetic Field of the Earth
    • Generated by the Earth’s core
    • Acts like a bar magnet
    • Magnetic poles not aligned with geographic poles
    • Inclined axis with respect to the rotation axis
    • Equation: $\mathbf{B=\mu_0(H+M)}$

Slide 26

  • Diamagnetic Materials (Continued)
    • Applications: Maglev trains, MRI machines, magnetic separators
    • Superconducting magnets for levitation and stability
    • Example: Magnetic levitation of a superconductor

Slide 27

  • Paramagnetic Materials (Continued)
    • Applications: MRI, particle accelerators, magnetic storage devices
    • Langevin’s Theory of Paramagnetism: $M = \frac{CNB}{T}$
    • Example: MRI machine and working principle

Slide 28

  • Ferromagnetic Materials (Continued)
    • Applications: Transformers, motors/generators, magnetic hard drives
    • Electric motor working principle
    • Hysteresis loop and magnetic memory
    • Example: Hysteresis loop of a ferromagnetic material

Slide 29

  • Magnetic Field of the Earth (Continued)
    • Earth’s magnetic dipole
    • Magnetic declination and inclination
    • Magnetosphere and solar wind protection
    • Example: Magnetic field lines around the Earth

Slide 30

  • Diamagnetic Materials (Continued)
    • Diamagnetic substances repel magnetic fields (weakly)
    • Applications in levitation, materials characterization
    • Example: Diamagnetic levitation of a frog
    • Equation: $\chi \approx -1$ (magnetic susceptibility)