Long-range non-collinear all-in/all-out magnetic order has been directly observed for the first time in real space in the pyrochlore Cd$_2$Os$_2$O$_7$ using resonant magnetic microdiffraction at the Os L$_3$ edge. Two different antiferromagnetic doma
ins related by time-reversal symmetry could be distinguished and have been mapped within the same single crystal. The two types of domains are akin to magnetic twins and were expected - yet unobserved so far - in the all-in/all-out model. Even though the magnetic domains are antiferromagnetic, we show that their distribution can be controlled using a magnetic field-cooling procedure.
The microscopic details of flux line lattice state studied by muon spin rotation is reported in an electron-doped high-$T_{rm c}$ cuprate superconductor, Sr$_{1-x}$La$_{x}$CuO$_{2}$ (SLCO, $x=0.10$--0.15). A clear sign of phase separation between mag
netic and non-magnetic phases is observed, where the effective magnetic penetration depth [$lambdaequivlambda(T,H)$] is determined selectively for the latter phase. The extremely small value of $lambda(0,0)$ %versus $T_{rm c}$ and corresponding large superfluid density ($n_s propto lambda^{-2}$) is consistent with presence of a large Fermi surface with carrier density of $1+x$, which suggests the breakdown of the doped Mott insulator even at the optimal doping in SLCO. Moreover, a relatively weak anisotropy in the superconducting order parameter is suggested by the field dependence of $lambda(0,H)$. These observations strongly suggest that the superconductivity in SLCO is of a different class from hole-doped cuprates.
