Neutron scattering can be very efficiently used for studying of magnetic vortex lattices (VL) (or flux-line lattices (FLL)) in unconventional superconductors. Actually, very first experimental evidence of VL existence after their theoretical prediction by Abrikosov [1] was conducted by means of neutron scattering [2] in Nb. Exploring of small angle neutron scattering (SANS) for direct observation of FLL [3] got “second - breath” with discovering of high-Tc superconductors (HTSC), which are all of type-II and with higher upper critical field Hc2. SANS is exceptional tool for establishing the values of HTSC.
Sr2RuO4, an isostructural of the high-Tc material La2-xSrxCuO4, is the first 2D perovskite oxide that exhibits superconductivity without copper [3]. Unlike La2-xSrxCuO4, however, it exhibits Fermi liquid behavior in its normal state. Sr2RuO4 then became an attractive material to probe the mechanism of high-Tc superconductivity, and also to study p-wave superconductivity since it has a simple band structure compared to Uranium based systems, another p-wave superconducting family. To this date, however, some groups still claim that there is no credible evidence of p-wave superconductivity of Sr2RuO4. Here, some first results of FLL in Sr2RuO4 measurements conducted at KWS-3 SANS facility are reported.
The measurements of dynamics of skyrmion lattice using neutron spin-echo technique is reported as well. Skyrmions are vortex-like magnetics structures, created in helimagnet (here was used single crystal MnSi). According to recent theoretical studies the lowest-energy excitations of the system are the so-called ‘phason’ modes of the skyrmion lattice. Their dispersion curves for the propagation vector (qz) parallel to the magnetic field are expected to be asymmetric along the strings of the skyrmions, indicating that the magnetic excitations have different q dependencies along +qz and –qz. This prediction was tested by a Spin-Echo technique that is sensitive to these low-energy excitations and to their momentum and it was showed that an asymmetric magnetic dispersion is present in the skyrmion state [4].