Positive muon diffusion in helicoidally-ordered antiferromagnets

A method for measuring the time scale for positive muon diffusion in helicoidally ordered antiferromagnets is proposed. The experiment shows that the muon diffusion in dusprosium over the temperature interval 100–175 K is a tunneling process.     

Monium acoustic resonance in alpha-quartz

The effect of acoustic oscillations of the -quartz crystalline lattice on the behaviour of muonium polarization has been studied experimentally. It is shown that when the frequency of the standing ultrasound wave coincides with one of the muonium quadrupole interaction frequencies a specific broadening of the muonium line occurs; that is a muonium acoustic resonance is observed. The possibilities of using this effect for investigating properties of solids by the SR method are discussed.     

Depolarization ofμ + muons in GaAs single crystals

ASR study has been carried out on high resistivity single crystal gallium arsenide (GaAs). Three characteristic states involving the ⁺ muon (Mu^*, Mu, ⁺ were shown to exist in a binary semiconductor, similar to the case of elemental semiconductors.     

Anisotropy of magnetic properties of textured superconductor Bi2Sr2CaCu2O8+δ

The values of the penetration depths and their temperature dependences were measured for differentc-axis orientations of a textured 2.2.1.2. sample. The remanent magnetic flux was studied. The giant mobility of the trapped vortex structure was found above 40 K.     

Zero field muon spin relaxation rate in the superconducting state of Nb3Al

It was shown that at T=12 k the dipole relaxation of a positive muon in Nb₃Al in the zero external magnetic field is well described by the Kubo-Toyabe function for the static distrubution of the dipole magnetic fields in the absence of muon diffusion. The superconducting state of Nb₃Al was used for eliminating the background from muons stopped in the cryostat walls.     

Investigation of muonium quadrupole interaction in α-quartz in the temperature region 75–120 K

The parameters of the muonium quadrupole interaction in α-quartz as well as the orientation of the EFG tensor principal axes are determined. It is shown that there is no temperature dependence of these characteristics in the temperature region 75–120 K. The assumption of the reversal of the sign of the q?uadrupole constant with temperature increase from 120 K to room temperature is confirmed. It is shown that the change of the quadrupole interaction strength and symmetry is caused by the diffusion of muonium.     

μSR study of the properties of Fe3O4-based nanostructured magnetic systems

A ferrofluid based on Fe₃O₄ nanoparticles dispersed in heavy water D₂O is studied using the μSR method. The experiment has been carried out at temperatures 26–300 K. It is found that the diamagnetic (muon) fraction is formed in the ferrofluid in about the same amount as in D₂O, but the muon-spin relaxation rate in the ferrofluid is much higher than in D₂O. A significant shift of the muon-spin precession frequency in the ferrofluid is observed. It is shown that the shift of the muon precession frequency as a function of the external magnetic field is described by the Langevin function typical of paramagnetic magnetization. The mean magnetic field in the medium due to magnetic-nanoparticle polarization in an external field is experimentally determined. The nanoparticle sizes are estimated.