Using the de Haas-van Alphen effect we have measured the evolution of the Fermi surface of BaFe2(As1-xPx){2} as a function of isoelectric substitution (As/P) for 0.41

We report the measurements of the de Haas-van Alphen (dHvA) effect for field ranges below and above the metamagnetic transition field (//m) in CeRu2Si2. The dHvA frequency branches and the effective masses ranging from 1.5A^7O to 120mo observed below Hm agree with the predictions of the itinerant / electron model, whereas those above Hm can be explained well with the localized / electron model. All the dHvA frequencies change abruptly around Hm-The effective masses decrease considerably around Hm and then continue to decrease with increasing field.

Quantum oscillations have been investigated far into the mixed state of the type II superconductor ZH-NbSei. The de Haas-van Alphen effect is found to persist to fields as low as -0 . 3 B a and to t e m p e r a m of -0.003Tc. A selfamistent band shuclure calcularion.performed for ?H-NbSez in the normal non-charge-density-wave state using a full potentid linearized augmented p h e wave (FLAPW) method, accounts well for the experimental angular dependence of the quantum oscillations in term of a small Ral hole Fermi surface around the r point. This feaNre derives mainly from chalcogen p bands and has a massenhancement &tor much smaller than expected from the specific heat QuanNm oscillations in the presence of the vortex lattice are observed to experience an additional damping, from which the order parameter is atimated to be A(0) = 0.6 f 0.1 meV.

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Measurements of the ac susceptibility, dc magnetization, magnetic relaxation, specific heat, and electrical resistivity of U 2 IrSi 3 are reported. The investigated compound crystallizes in an AlB 2 -derived hexagonal structure and undergoes a ferromagnetic cluster glass transition at T f ϭ10.5 K. Typical features of the ferromagnetic cluster glass state include ͑i͒ a frequency-dependent cusp in the ac susceptibility, ͑ii͒ an irreversibility in the temperature dependence of the dc magnetization, ͑iii͒ a very slow decay of the remanence, ͑iv͒ a small jump in the initial magnetization curve, and ͑v͒ a small specific heat anomaly, which contains a very small amount of magnetic entropy. The specific heat data also demonstrate a large value of the linear specific heat coefficient and the absence of true long-range magnetic order. Furthermore, a Kondo-effect-like behavior is observed in the temperature dependence of the electrical resistivity. It seems that both cluster glass freezing and Kondo-lattice effects make an impact on the low-temperature physical properties of U 2 IrSi 3 .