Vortex lattice transition in d-wave superconductors

Abstract

Making use of the extended Ginzburg-Landau theory, which includes the fourth-order derivative term, we study the vortex state in a magnetic field parallel to the c axis. The vortex core structure is distorted due to the higher-order term, which reveals the fourfold symmetry. Further, this distortion gives rise to the core interaction energy which favors a square lattice tilted by 45° from the a axis. The triangular vortex lattice in small field region transforms into the rhombic vortex lattice (i.e., the square vortex lattice tilted 45° from the a axis) at B=Hcr∼κ−1Hc2(t), where κ is the Ginzburg-Landau parameter and Hc2(t) is the upper critical field. Therefore, in most of the B−T phase diagram the vortex lattice is rhombic. The transition is of the second order and the associated jump in the specific heat should be accessible experimentally.

Source-reported materials — not catalogue approval

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