3d magnetic dopant atoms in transition-metal superconductors. Part I. Localized magnetic moments on chromium and manganese dopant atoms in niobium and vanadium. Part II. The effects of chromium and manganese dopant atoms on the upper critical magnetic field of niobium

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5790298

Roy, A

In Part I the experimental situation regarding the presence of localized magnetic moments on 3d dopant atoms in transition-metal superconductors is reviewed, and the salient features of some traditional theories of localized moments in metals are described. It is indicated why the magnetic behavior of the host-metal ions may be significant in the case of transition-metal hosts, and a simple model in which the effects of host-metal magnetism are included is presented. An account is then given of magnetic susceptibility measurements on films of Nb and V, pure and doped with Cr and Mn. The data in terms of the model is discussed. Results indicate the presence of localized magnetic moments on Cr and Mn dopant atoms in both Nb and V. In Part II the theories of magnetically doped superconductors are reviewed briefly. An account of measurements of the superconducting transition temperature, T/sub c/, and of the upper critical magnetic field, H/sub c2/(T) of several Nb films pure and doped with Cr and Mn are then given. The superconducting properties of these films are related to various normal state material parameters, and the implications of these relations on the superconductivity of Nb are discussed. It was found that T/sub c/ of Nb is decreased in the presence of Cr or Mn, by amounts consistent with the existence of localized moments. Results for H/sub c2/(T) indicate, for both Cr and Mn dopants in Nb, that the pair-breaking effect of the magnetic dopants is additive with the pair-breaking effect of the applied magnetic field, and is possibly temperature-independent.

• Research Organization: Illinois Univ., Urbana (USA)
• OSTI ID: 5790298
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
CHROMIUM
CRITICAL FIELD
DOPED MATERIALS
ELEMENTS
MAGNETIC FIELDS
MAGNETIC MOMENTS
MANGANESE
MATERIALS
METALS
NIOBIUM
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
TRANSITION TEMPERATURE
VANADIUM