Effect of a quartic anisotropy energy on the ''spiral magnetic'' coexistence state of superconductivity and ferromagnetism

Journal Article · Mon Feb 01 00:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.1680· OSTI ID:5680214

Rose, G H; Hu, C

The effect of three types of ''quartic'' anisotropy energy (i.e., in the M/sup 4/ term of the magnetic Ginzburg-Landau free energy) on the polarization of the ''spiral magnetic'' state of Blount and Varma is studied near the onset temperature. For a quartic anisotropy with uniaxial symmetry, we find continuous polarization transitions from circular to elliptical and then to linear as the strength of a uni-easy-axis anisotropy is increased. (No transition is found for the uni-hard-axis case.) If the quartic anisotropy has cubic symmetry, we find a discontinuous transition directly between circular and linear, without going through an elliptic stage, when the sign of the anisotropy energy is to favor the cubic axes. (The polarization stays circular at all strengths of the anisotropy energy if the sign of the latter is to favor the body diagonals.) Finally, we model the anisotropy in primitive tetragonal ErRh/sub 4/B/sub 4/ with a quadratic anisotropy giving a hard c axis, plus a quartic anisotropy in the basal plane with a square symmetry. A first-order polarization transition directly between circular and linear is also obtained for this case, when the quartic anisotropy favors the principal axes in the basal plane. This last case studied provides a plausible explanation for the linear polarization observed in the coexistence state of ErRh/sub 4/B/sub 4/. .AE

• Research Organization: Center for Theoretical Physics, Department of Physics, Texas AandM University, College Station, Texas 77843
• OSTI ID: 5680214
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 37:4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ERBIUM BORIDES
FERROMAGNETISM
SUPERCONDUCTIVITY
FERROMAGNETIC MATERIALS
HOLMIUM BORIDES
SUPERCONDUCTORS
ANISOTROPY
FREE ENERGY
GINZBURG-LANDAU THEORY
INTERMEDIATE STATE
MAGNETIC FIELDS
MAGNETIZATION
BORIDES
BORON COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
ERBIUM COMPOUNDS
HOLMIUM COMPOUNDS
MAGNETIC MATERIALS
MAGNETISM
MATERIALS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
THERMODYNAMIC PROPERTIES
360204* - Ceramics
Cermets
& Refractories- Physical Properties
656100 - Condensed Matter Physics- Superconductivity