Signatures of new d-wave vortex physics in overdoped Tl2Ba2CuO(6+x) revealed by TF-µ(+)SR.

The spontaneous expulsion of applied magnetic field, the Meissner effect, is a defining feature of superconductors; in Type-II superconductors above the lower critical field, this screening takes the form of a lattice of magnetic flux vortices. Using implanted spin-1/2 positive muons, one can measure the vortex lattice field distribution through the spin precession and deduce key parameters of the superconducting ground state, and thereby fundamental properties of the superconducting pairing. Muon spin rotation/relaxation (µSR) experiments have indeed revealed much interesting physics in the underdoped cuprates, where superconductivity is closely related to, or coexistent with, disordered or fluctuating magnetic and charge excitations.

Bound magnetic polarons in the 3d-electron ferromagnetic spinel semiconductor CdCr2Se4.

Muon spin rotation/relaxation spectroscopy has been employed to study electron localization into a bound magnetic polaron around the positive muon in the 3d magnetic spinel semiconductor CdCr2Se4 at temperatures up to 300 K (far above the ferromagnetic transition at Tc = 130 K) in magnetic fields up to 7 T. Electron localization into a magnetic polaron occurs due to its strong exchange interaction with the magnetic 3d electrons of local Cr(3 +) ions, which confines its wavefunction to within R≈0.3 nm, allowing significant overlap with both the nearest and the next nearest shells of Cr ions.

Spin polarons in the correlated metallic pyrochlore Cd2Re2O7.

Muon spin rotation spectroscopy reveals localized electron states in the geometrically frustrated metallic pyrochlore Cd2Re2O7 at temperatures from 2 to 300 K in transverse magnetic fields up to 7 T. Two distinctive types of localized states, with characteristic radii of about 0.5 and 0.