Thermodynamics, Statistical Physics, and Quantum Mechanics

THERMODYNAMICS AND STATISTICAL PHYSICS 49

For an adiabatic process, show that the ratio of final and initial tem-

peratures is given by

d) Explain and indicate in the diagram given in Figure P.4.105 a

possible route for the adiabatic demagnetization cooling process to

approach zerotemperature.

4.106 Critical Field in Superconductor (Stony Brook,

Chicago)

Consider a massive cylinder of volume V made of a type I superconducting
material in a magnetic field parallel to its axis.

a) Using the fact that the superconducting statedisplays perfect diamag-

netism,whereas the normal state has negligible magnetic susceptibil-

ity, show that the entropy discontinuity across the phase boundary is

at zero field H:

where is the critical H field for suppressing superconductivity

at a temperature

What is the latent heat when the transition occurs in a field?

What is the specificheatdiscontinuity in zero field?

b)

c)