The figure schematically shows the $M$ (magnetization) - $H$ (magnetic field) plots for certain types of materials. Here $M$ and $H$ are plotted in the same scale and units. Which one of the following is the most appropriate combination?
To determine the correct combination of materials based on the magnetization ($M$) versus magnetic field ($H$) plots, we must understand the typical behavior of different magnetic materials:
- Diamagnetic Materials: These materials generate a weak magnetic moment in the opposite direction to the applied magnetic field. The magnetization curve is typically a straight line with a negative slope. Therefore, plot (Q) represents diamagnetic materials.
- Paramagnetic Materials: These materials have unpaired electrons, causing them to be weakly attracted by a magnetic field. The magnetization is proportional to the applied field, showing a straight line with a positive slope passing through the origin. Thus, plot (P) corresponds to paramagnetic materials.
- Type-I Superconductors: These exhibit perfect diamagnetism below their critical field, transitioning from a zero magnetization state abruptly. This behavior is demonstrated by plot (R), where the magnetization drops to zero indicating the exclusion of magnetic fields.
With this understanding, the most appropriate combination is (P) - Paramagnet; (Q) - Diamagnet; (R) - Type-I Superconductor.
Important Questions from Superconductivity Meissner Effect BCS Theory
Consider a metal-superconductor junction connected to a dc voltage $V$. At $T < T_c$, where $T_c$ is the superconductor's transition temperature, the current $I$ versus $V$ behavior of this junction is shown schematically in the figure below. If the superconducting energy gap is $D \text{ meV}$. The value of $D$ (rounded off to one decimal place) is _____
- Which of the following option(s) is/are correct for a Type I superconductor?
- A material behaves as a superconductor below a critical temperature $T_c$ and as a normal conductor above $T_c$. A magnetic field $\vec{B} = B\hat{z}$ is applied when $T > T_c$. The material is then cooled below $T_c$ in the presence of $\vec{B}$. Which of the following figure represent the correct configuration of magnetic field lines?
- Amongst electrical resistivity ($\rho$), thermal conductivity ($\kappa$), specific heat ($C$), Young's modulus ($Y$), and magnetic susceptibility ($\chi$), which quantities show a sharp change at the superconducting transition temperature?
- At $T = 0$ K, which of the following diagram represents the occupation probability $P(E)$ of energy states of electrons in a BCS type superconductor?
