Neutron studies of the flux-line lattice in high temperature superconductors

Don Paul, Ted Forgan, Bob Cubitt, Steve Lee, Mahana Yethiraj, Herb Mook

Research output: Contribution to journalReview articlepeer-review


In a type II superconductor, such as the Nb or the high temperature superconductors, there are two critical magnetic fields, HC1 and HC2. When a sample is cooled through the critical temperature for superconductivity, TC in a magnetic field of less than HC1 all magnetic flux is expelled from the material-the Meissner-Ochsenfeld effect. HC2 is the maximum magnetic field which can be applied to the superconductor without driving the sample back into the normal state. At intermediate magnitudes of magnetic field, HC1<H<HC2 a superconducting sample is in the mixed state where magnetic flux still exists within the bulk of the material. In this mixed state, the magnetic flux enters as “flux-lines”; each one of these objects has a normal core which is surrounded by a circulating supercurrent flow and contains a total amount of flux equal to h/2e. At low fields, these flux-lines are independent, but in higher fields their magnetic fields and supercurrents overlap. In response to this interaction, the flux-lines rearrange themselves to minimize their free energy. This arrangement is usually in the form of a two-dimensional, hexagonal lattice. A fluxline has a core of radius ζ the coherence length or minimum length scale for variations in the superconducting wavefunction, and is surrounded by a spatially, decaying magnetic induction on the length scale of the penetration depth, λ. In the past, neutron diffraction experiments have played an important role in determining the properties of flux-line lattices in conventional superconductors.

Original languageEnglish
Pages (from-to)18-23
Number of pages6
JournalNeutron News
Issue number3
Publication statusPublished - 1996


Dive into the research topics of 'Neutron studies of the flux-line lattice in high temperature superconductors'. Together they form a unique fingerprint.

Cite this