Evidence for triplet superconductivity in a superconductor-ferromagnet spin valve.

We have studied the dependence of the superconducting (SC) transition temperature on the mutual orientation of magnetizations of Fe1 and Fe2 layers in the spin valve system CoO(x)/Fe1/Cu/Fe2/Pb. We find that this dependence is nonmonotonic when passing from the parallel to the antiparallel case and reveals a distinct minimum near the orthogonal configuration. The analysis of the data in the framework of the SC triplet spin valve theory gives direct evidence for the long-range triplet superconductivity arising due to noncollinearity of the two magnetizations.

Slow magnetic relaxations in manganese(III) tetra(meta-fluorophenyl)porphyrin-tetracyanoethenide. Comparison with the relative single chain magnet ortho compound.

Mn(III) tetra(meta-fluorophenyl)porphyrin-tetracyanoethenide coordination polymer (abbreviated meta-F) was synthesized and crystallographically and magnetically characterized. The compound crystallizes in the space group C2/c with four equivalent molecules in the unit cell arranged along two symmetry related nonparallel linear chain directions. Magnetic properties were studied by SQUID dc magnetization and ac susceptibility techniques and high field-high frequency electron spin resonance (HF-ESR). Glassy transition to a ferromagnetic-like state is observed at 10 K accompanied by slow magnetic relaxations. The glassiness is interpreted as due to 3D domain wall pinning. In a bias dc magnetic field the width of the relaxation time distribution decreases and the relaxations become similar to the relaxations of the single chain magnet Mn(III) tetra(ortho-fluorophenyl)porphyrin-tetracyanoethenide (abbreviated ortho-F), for which comparative HF-ESR studies were also conducted in this work. Magnetic properties of these two compounds are compared, and the nature of magnetic relaxations in meta-F is discussed.

Magneto-structural correlations in oxalate-bridged Sr(ii)Cr(iii) coordination polymers: structure, magnetization, X-band, and high-field ESR studies.

The results of high-field electron spin resonance (HF-ESR) spectroscopy on the title 1D coordination polymers at frequencies up to 415 GHz, supported by X-ray diffraction, thermal, magnetic susceptibility, and X-band (10 GHz) ESR studies, are presented. The heterometallic compounds {SrCr2(phen)2(C2O4)4}·H2O (SrCrPhen) and {SrCr2(bpy)2(C2O4)4(H2O)}·5H2O (SrCrBpy) (phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine) were synthesized. Structural analysis revealed double oxalate-bridged zigzag Sr-Cr chains while magnetic susceptibility studies showed paramagnetic behaviour of the complexes. HF-ESR spectroscopy data were analysed with a relevant spin-Hamiltonian, yielding the g, D and E parameters of the Cr(iii) ions. Both complexes showed small magnetic easy-axis type anisotropy with |D| ∼ 1 K; SrCrBpy has uniaxial anisotropy while SrCrPhen has biaxial anisotropy. HF-ESR studies have enabled us to establish rational magneto-structural correlations and revealed significant differences between very similar crystal structures. Additionally, the ability of SrCrPhen and SrCrBpy to be single-source precursors for the formation of Sr-Cr oxides was investigated.

Magnetic moments and exchange coupling in nitride clusterfullerenes Gd(x)Sc(3-x)N@C80 (x = 1-3).

The magnetic properties of nitride clusterfullerenes GdxSc3-xN@C80 (x = 1-3) are studied as a function of the number of Gd atoms in the cluster. The intracluster interaction of the Gd ions in Gd2ScN@C80 and Gd3N@C80 is ferromagnetic with exchange constants of -1.2 K ± 0.1 K and -0.6 K ± 0.1 K, respectively. At 2 K, the magnetization curves exhibit noticeable deviations from the Heisenberg model pointing to a non-negligible anisotropy.