arXiv subjects

J. L. Gavilano

Publications and source records attributed to J. L. Gavilano.

39 records · Page 3Linked to original sources

arXiv2001

Anomalous NMR response of quasicrystalline icosahedral A_{72.4}Pd_{20.5}Mn_{7.1} at low temperatures

We report the observation of an anomalous {27}Al-NMR response of a single grain Al_{72.4}Pd_{20.5}Mn_{7.1} icosahedral quasicrystal at low temperatures. In an external magnetic field of 6 T and upon decreasing temperature, we observe a sharp 100 % increase of the resonance linewidth at 2.5 K. No further changes of the linewidth are observed down to 0.05 K. The linewidth enhancement is accompanied by a small but distinct increase of the spin-lattice relaxation rate T_{1}^{-1} and by a maximum of the spin-spin relaxation time T_{2}(T). All these anomalies are absent in external fields of 2.5 T and below. Our observations indicate unusual variations in the stability of isolated magnetic moments in a quasiperiodic metallic environment.

cond-mat.mtrl-sci↗

arXiv2001

Anomalous NMR Spin-Lattice Relaxation in SrB_{6} and Ca_{1-x}La_{x}B_{6}

We report the results of {11}B nuclear magnetic resonance (NMR) measurements of SrB_{6} and Ca_{0.995}La_{0.05}B_{6} below room temperature. Although the electrical resistivities of these two materials differ substantially, their {11}B-NMR responses exhibit some strikingly common features. Both materials exhibit ferromagnetic order, but their {11}B-NMR spectra reveal very small hyperfine fields at the Boron sites. The spin lattice relaxation T_{1}^{-1} varies considerably with external field but changes with temperature only below a few K. We discuss these unusual results by considering various different scenarios for the electronic structure of these materials.

cond-mat.str-el↗

arXiv2000

LiVGe2O6, an anomalous quasi 1D, $S = 1$ system, as revealed by NMR

We report the results of $^{7}$Li nuclear magnetic resonance (NMR) studies of LiVGe$_{2}$O$_{6}$, a quasi one--dimensional spin $S = 1$ model system, at low temperatures. Our data, including NMR spectra and the temperature dependence of the spin-lattice relaxation rate $T_{1}^{-1}$, indicate a first order phase transition to occur at $T_{c}\simeq 23$ K. The NMR response of LiVGe$_{2}$O$_{6}$ below $T_{c}$ suggests that the ordered phase is antiferromagnetic and has unusual features. Possible reasons for this unexpected behavior are discussed.

cond-mat.str-el↗