Strong-Coupling Effects in "Dirty" Superfluid 3He^3He

The contribution of the strong-coupling effects to the free energy of the "dirty" superfluid $^3He$ is estimated using a simple model. It is shown that the strong-coupling effects are less susceptible to the quasiparticle scattering events in comparison to the weak-coupling counterpart. This supports the conclusion about stabilization of the $B$-phase in aerogel environment at pressures where the $A$-phase takes over in bulk superfluid $^3He$, in accordance with recent experimental observations in zero magnetic field.Comment: 10 pages, LaTeX file. This is a revised version of the paper with some additional comments and references, and corrected typos. Submitted to Journal of Physics: Condensed Matte

NMR in Superfluid A-like Phase of 3^3He Confined in Globally Deformed Aerogel in Tilted Magnetic Field

NMR spectra in superfluid A-like phases confined in axially deformed aerogel in presence of a magnetic field inclined with respect to deformation axis is considered. The characteristic features of dipole frequency shift in axially compressed and axially stretched cases are compared. In particular, it is shown that in axially stretched aerogel environment the stability region of coherently spin precessing mode is rather narrow due to the U(1)LIM effect.Comment: 8 pages, 2 figure

Stable Spin Precession at one Half of Equilibrium Magnetization in Superfluid 3He-B

New stable modes of spin precession have been observed in superfluid 3He-B. These dynamical order parameter states include precession with a magnetization S=pS_{eq} which is different from the equilibrium value S_{eq}. We have identified modes with p=1, 1/2 and \approx 0. The p=1/2 mode is the second member of phase correlated states of a spin superfluid. The new states can be excited in the temperature range 1-T/T_c \lesssim 0.02 where the energy barriers between the different local minima of the spin-orbit energy are small. They are stable in CW NMR due to low dissipation close to T_c.Comment: submitted to Physical Review Letters, 4 pages, revtex, 4 Figures in ftp://boojum.hut.fi/pub/publications/lowtemp/LTL-96005.p

Calculation of NMR Properties of Solitons in Superfluid 3He-A

Superfluid 3He-A has domain-wall-like structures, which are called solitons. We calculate numerically the structure of a splay soliton. We study the effect of solitons on the nuclear-magnetic-resonance spectrum by calculating the frequency shifts and the amplitudes of the soliton peaks for both longitudinal and transverse oscillations of magnetization. The effect of dissipation caused by normal-superfluid conversion and spin diffusion is calculated. The calculations are in good agreement with experiments, except a problem in the transverse resonance frequency of the splay soliton or in magnetic-field dependence of reduced resonance frequencies.Comment: 15 pages, 10 figures, updated to the published versio

Fermions on half-quantum vortex

The spectrum of the fermion zero modes in the vicinity of the vortex with fractional winding number is discussed. This is inspired by the observation of the 1/2 vortex in high-temperature superconductors (Kirtley, et al, Phys. Rev. Lett. 76 (1996) 1336). The fractional value of the winding number leads to the fractional value of the invariant, which describes the topology of the energy spectrum of fermions. This results in the phenomenon of the "half-crossing": the spectrum approaches zero but does not cross it, being captured at the zero energy level. The similarity with the phenomenon of the fermion condensation is discussed.Comment: In revised version the discussion is extended and 4 references are added. The paper is accepted for publication in JETP Letters. 10 pages, LaTeX file, 3 figures are available at ftp://boojum.hut.fi/pub/publications/lowtemp/LTL-96004.p

Genetic diversity of Erwinia amylovora isolates from fire blight diseased trees in Central and Eastern Georgia

The genetic diversity of 52 Erwinia amylovora isolates from pome fruit trees with fire blight in Central and Eastern Georgia from the years 2020–2022 was examined using specific PCR and genotyping of CRISPR repeat regions 1 and 2. The analysis identified three distinct genotypes: (A, a, α), matching historical Western European strains; (A, z, α), distinctive for Georgia and differing by a three-spacer deletion in CRR2 (2034–2036); as well as novel genotype (A, ä, α), which was not observed previously. Genotypes (A, a, α) and (A, z, α) were found to coexist geographically in all four regions investigated, whereas genotype (A, ä, α) was reported only in one case in the region of Kvemo Kartli. On separate instances, multiple genotypes were detected even within the same orchard or tree, illustrating the complex genetic landscape of E. amylovora in the country