J. Phys. I France
Volume 1, Numéro 8, August 1991
Page(s) 1155 - 1163
DOI: 10.1051/jp1:1991197
J. Phys. I France 1 (1991) 1155-1163

Superconducting kernel symmetry for an anisotropic superconductivity near $H_{\rm C2}$ and phase transitions in UPt 3

I. Luk'yanchuk

L.D. Landau Institute for Theoretical Physics, Kosygina 2, Moscow, 117940, U.S.S.R.

(Received 10 April 1991, accepted 25 April 1991)

The symmetry group of anisotropic Cooper pairing in magnetic field H includes the magnetic translations and rotations around H. On the basis of these operations Kasimir's operator which classifies the superconducting nuclei near $H_{\rm C2}$ is constructed. Such kernel classification is used to find all possible reasons of kink in $H_{\rm C2}(T)$-dependence existence and to interpret the phase transitions in H-T plane in the heavy-fermion superconductor UPt 3 at the assumption of two superconducting states coexistence. The phase transition lines in space nonuniform state $H_{\rm C1}<H<H_{\rm C2}$ is shown to be either the lines of superconducting order parameter parity violation with respect to reflection in a perpendicular to magnetic field plane or the lines of triangular vortex lattice distortion or the lines of Abricosov's lattice period multiplication. Last case near $H_{\rm C1}$ signifies the phase transition with changing of magnetic vortex quantization.

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