Transverse Magnetic Field Distribution in the Vortex State of Noncentrosymmetric Superconductor with O Symmetry

Abstract

We investigate the magnetic field distribution inside a Type II superconductor which has point group symmetry O such as Li2Pt3B. The absence of inversion symmetry as a departure from perfect cubic group O h causes a magnetization collinear with the phase gradient associated with the order parameter, and a component of current collinear with the local magnetic field. In the vortex state, we predict, by solving the Maxwell equation, a local magnetic field transverse to the vortex lines. The probability distribution of this transverse field is also obtained for the prospective muon-spinrotation measurements.

Rotation of the magnetic vortex lattice in Ru7B3 driven by the effects of broken time-reversal and inversion symmetry

“…While, to date, the theories focusing on gap and Fermi velocity anisotropy have not been adapted for NCS superconductors, the effect of broken inversion symmetry on the VL has been the subject of multiple studies [8,[27][28][29][30], which have focused on the C 4v and O crystallographic point groups. Perhaps the most striking result from these investigations has been the appearance of a transverse component of magnetic field in the vortex lattice [9,27,28,[31][32][33], which arises due to currents flowing parallel to the vortex which are unique to NCS systems. Further, the emergence of a new gap-amplitude modulated phase has been predicted in superconductors with non-zero Rashba-type spin-orbit coupling, which should have a strong effect on the VL coordination [29,30], although to date neither of these has been directly observed.…”

Magnetoelectric Effects, Helical Phases, and FFLO Phases

“…The solution in this case was found in Ref. [12,13]. The modified London equation is (the problem does not depend upon field direction)…”

“…Here we focus (as above) on two examples with point groups O and C 4v and provide the solutions of Refs. [18,19,12,13]. The approach used in these publications is to consider the parameter σ i j /λ to be small and then the Lifshitz invariants perturb the usual London solution.…”

“…A key new feature of non-centrosymmetric superconductors is the existence of Lifshitz invariants in the Ginzburg Landau (GL) free energy [3,4,5,6,7,8]. These give rise to magnetoelectric effects [9,10,5,11,12,13], helical phases [6,14,7,15,16], and novel magnetic properties [9,7,17,18,19,12] discussed in this chapter. To examine the consequences of these invariants we initially consider a GL theory for a single component order parameter (for example, an s-wave superconductor) and add the most general Lifshitz invariant allowed by broken inversion symmetry.…”

Adherence of the rotating vortex lattice in the noncentrosymmetric superconductor Ru7B3 to the London model

“…The emergence of the magnetoelectric effect directly affects the VL, as there is a complex array of shielding currents associated with the flux lines. Several theoretical studies have been done in this regard, with predictions of an altered vortex structure [8,24] and the possibility of tangential components of the magnetic field [25][26][27]. Nevertheless, these contributions are considered to be small and would be difficult to observe with conventional probes of condensed matter.…”