Zero Field Splitting Parameter of Mn²⁺-Doped Tl₂Cd₂(SO₄)₃ Single Crystals at Axial Symmetry Site

A variable temperature EPR study of Mn(2+)-doped NH(4)Cl(0.9)I(0.1) single crystal at 170 GHz: zero-field splitting parameter and its absolute sign.

EPR measurements have been carried out on a single crystal of Mn(2+)-doped NH(4)Cl(0.9)I(0.1) at 170-GHz in the temperature range of 312-4.2K. The spectra have been analyzed (i) to estimate the spin-Hamiltonian parameters; (ii) to study the temperature variation of the zero-field splitting (ZFS) parameter; (iii) to confirm the negative absolute sign of the ZFS parameter unequivocally from the t...

Remarks on the U ( 1 ) axial symmetry in QCD at zero and non – zero temperature

This paper is organized in two parts. The first part (Sections 2–5) is dedicated to the theory at T = 0 and contains a pedagogical review of some fundamental aspects related with the chiral symmetries of QCD, the U(1) problem and its solution proposed by ’tHooft, Witten and Veneziano. In the second part (Sections 6–14) we discuss the role of the U(1) axial symmetry for the phase structure of QC...

Order Parameter Symmetry in Doped YBCO Systems

Intense experimental and theoretical efforts have recently been brought to bear on the determination of the symmetry of superconducting order parameter in high Tc Cuprates as this would shed light on the nature of microscopic interactions that are responsible for superconductivity in these unusual systems. We use a two band model that reproduces the Fermi surface seen in ARPES experiments of Sh...

Field and angular dependence of the Sommerfeld coefficient in Al-doped MgB2 single crystals

Zero-Field Splitting Parameters D of Macrocyclic Systems*

The triplet zero-field splitting parameters D of [4n]and [4n + 2]-annulenes are calculated within a n-model. The dependence of D on n and the degree of bond lengths alternation is compared with that of ground state properties like magnetic ring currents. Furthermore it is shown that corannulenes which consist of two concentric perimeters with connecting radial bonds cannot be regarded as macroc...