Amalia Coldea

Abstract:

The first molecular material with the coexistence of ferromagnetism, metal-like conductivity, and chirality has been prepared using an organic/inorganic approach. In this case, a two-dimensional packing of chiral organic radical cations (responsible for both the electrical conductivity and optical activity) was assembled with a layered bimetallic oxalate-based anionic network (responsible for the magnetic properties). Shubnikov-de Haas oscillations confirmed the presence of a Fermi surface even when the transport properties suggested "insulating"-type behavior at very low temperatures.

Abstract:

In the quasi-one-dimensional cuprate PrBa2 Cu4 O 8, the Pr cations order antiferromagnetically at 17 K in zero field. Through a combination of magnetic susceptibility, torque magnetometry, specific heat, and interchain transport measurements, the anisotropic temperature-magnetic-field phase diagram associated with this ordering has been mapped out. A low-temperature spin-flop transition in the Pr sublattice is found to occur at the same magnetic field strength and orientation as a dimensional crossover in the ground state of the metallic-CuO chains. This coincidence suggests that the spin reorientation is driven by a change in the anisotropic Rudermann-Kittel-Kasuya-Yosida interaction induced by a corresponding change in effective dimensionality of the conduction electrons. © 2010 The American Physical Society.

Abstract:

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

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