Fractional Flux Quantization in Loops of Unconventional Superconductors

Abstract

The magnetic flux threading a conventional superconducting ring is typically quantized in units of ${\Phi }_0=hc/2e$. The factor 2 in the denominator of ${\Phi }_0$ originates from the existence of two different types of pairing states with minima of the free energy at even and odd multiples of ${\Phi }_0$. Here we show that spatially modulated pairing states exist with energy minima at fractional flux values, in particular at multiples of ${\Phi }_0/2$. In such states condensates with different center-of-mass momenta of the Cooper pairs coexist. The proposed mechanism for fractional flux quantization is discussed in the context of cuprate superconductors, where $hc/4e$ flux periodicities as well as uniaxially modulated superconducting states were observed.

5 pages, 3 figures

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Cited by in corpus (1)

• Pressure-induced collapsed-tetragonal phase in SrCo2As2