Magnetic field splitting of the density of states of thin superconductors
Using Green's-function techniques, we present a theoretical calculation of the behavior of the density of states, free energy, and order parameter of very thin superconductors in a high magnetic field as a function of spin-orhit and spin-flip impurity scattering. In very thin superconducting films without spin scattering, the upper critical field is determined by the Pauli paramagnetism of the nomnal-metal electrons. Tunneling measurements by Meservey and Tedrow have shown a spin splitting by 2 mu /sub B/H in energy space of the BCS peak in the density of states. Zero-temperature calculations of the separate up- and down-spin Green's function for a superconductor show that spin-orbit impurities destroy the magnetic field separation of the peaks in the density of states but do not destroy the energy gap. Spin-flip scattering is much more destructivc and destroys both the separation oi the peaks and the energy gap. We generalize the calculation to T plus or minus 0 and calculate and plot the critical field versus temperature and the magnetic field dependence of the free energy and order parameter for the various values of the spin-orbit and spin-flip parameter. We also use the theoretical calculations to obtain a fit to the low- temperature tunneling data of Meservey and Tedrow between thin Al and a normal metal and the spin-polarized tunneling between thin Al and ferromagnetic metals. (auth)
- Research Organization:
- Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-022711
- OSTI ID:
- 4339735
- Journal Information:
- Phys. Rev., B, v. 8, no. 7, pp. 3161-3178, Journal Name: Phys. Rev., B, v. 8, no. 7, pp. 3161-3178; ISSN PLRBA
- Country of Publication:
- United States
- Language:
- English
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