[GATE 2021] Saturation Magnetization of Nickel Quiz
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Questions and Answers

Which of the following best describes the behavior of the order parameter just below the Curie temperature, where (T - T_C) is very small?

  • M is proportional to $(T_C - T)^{1/2}$
  • M is proportional to $(T_C - T)^{1/3}$
  • M is proportional to $(T_C - T)$
  • M is proportional to $(T_C - T)^{3/2}$ (correct)
  • What is the relation between the magnetization (M) and temperature (T) for the given system described by the equation M = tanh(M/T)?

  • The system will show a second-order phase transition at T = 1
  • The system will show a second-order phase transition at T = 1/2 (correct)
  • The system will show a first-order phase transition at T = 1
  • The system will not show any phase transition at any temperature
  • For a ferromagnetic material, the free energy is given by F = F_0 + a_0 (T - T_C) M^2 + bM^4, where F_0, a_0, and b are positive constants. How is the relation between M^2 and T best depicted?

  • A straight line with a positive slope
  • A curve with a non-zero maximum at T = T_C (correct)
  • A straight line with a negative slope
  • A curve with a non-zero minimum at T = T_C
  • How does the Pauli paramagnetic susceptibility of a metal at low temperatures depend on temperature T?

    <p>It is proportional to T</p> Signup and view all the answers

    In the provided figure, which point on the curve represents the transition from the paramagnetic to the ferromagnetic phase?

    <p>The point where the curve has a maximum value</p> Signup and view all the answers

    Which of the following temperatures is known as the Curie temperature for a ferromagnetic material?

    <p>The temperature at which the material becomes paramagnetic</p> Signup and view all the answers

    Which of the following statements accurately describes the behavior of magnetic susceptibility $\chi$ for paramagnetic materials?

    <p>$\chi$ is positive and decreases with increasing temperature.</p> Signup and view all the answers

    In ferromagnetic materials, what happens to the magnetic susceptibility $\chi$ as the temperature approaches the Curie temperature $T_C$?

    <p>$\chi$ approaches infinity.</p> Signup and view all the answers

    For an antiferromagnetic material, what is the relationship between the magnetic susceptibility $\chi$ and the Néel temperature $T_N$?

    <p>$\chi$ is positive and decreases with increasing temperature above $T_N$.</p> Signup and view all the answers

    What is the significance of the Curie temperature $T_C$ in ferromagnetic materials?

    <p>It is the temperature at which the material loses its spontaneous magnetization.</p> Signup and view all the answers

    In the given question, the saturation magnetization of Nickel in its ferromagnetic state is related to which of the following properties?

    <p>All of the above.</p> Signup and view all the answers

    Based on the given magnetic susceptibility graphs, which curve corresponds to an antiferromagnetic material?

    <p>Curve C</p> Signup and view all the answers

    What is the relationship between the zero-field magnetic susceptibility and the spontaneous magnetization M(0) at T = 0 K?

    <p>$\chi_0 = \frac{1}{1 - M(0)^2}$</p> Signup and view all the answers

    For a ferromagnet, what is the relationship between the magnetization M, temperature T, magnetic field H, Curie constant C, and Weiss molecular field constant θ?

    <p>M = C(H/T) tanh(θM/T)</p> Signup and view all the answers

    What are the values of the Curie constant C and the Weiss molecular field constant θ in CGS units, as given in the text?

    <p>C = 3 × 10^2, θ = -2 × 10^4</p> Signup and view all the answers

    For the paramagnetic atomic gas described in the text, what is the expected value of the paramagnetic susceptibility?

    <p>The susceptibility decreases with increasing temperature.</p> Signup and view all the answers

    What is the significance of the Curie temperature T_C in ferromagnets?

    <p>It is the temperature above which the material becomes paramagnetic.</p> Signup and view all the answers

    In the hysteresis loop shown in the figure, what is the expected behavior at a temperature of 38 K?

    <p>The loop will have a smaller area, indicating weaker ferromagnetic behavior.</p> Signup and view all the answers

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