A. García-Santiago

Enhanced pinning in a magnetic-superconducting bilayer

Pinning of vortices in a high-temperature superconductor by the magnetic domain structure of a highly anisotropic ferromagnet is investigated by means of magnetic measurements in nanoscale period superconductor/ferromagnet (SC/FM) heterostructures. Two different samples consisting of highly epitaxial films of YBa2Cu3O7(SC) and BaFe12O19(FM) are analyzed relative to a pure superconducting YBa2Cu3O7 film. The irreversibility line obtained in the magnetic-field-reduced-temperature phase diagram for each heterostructure is found to shift upwards when compared to the line corresponding to the pure superconducting sample. This effect is interpreted as an evidence for the enhancement of pinning of vortices in the SC layer by the magnetic domain structure in the FM layer.

Quantum magnetic deflagration in Mn12 acetate

We report controlled ignition of magnetization reversal avalanches by surface acoustic waves in a single crystal of

Acoustomagnetic pulse experiments in LiNbO3∕Mn12 hybrids

{\mathrm{Mn}}_{12}

Low-temperature microwave emission from molecular clusters

acetate. Our data show that the speed of the avalanche exhibits maxima on the magnetic field at the tunneling resonances of

Emergence of the stripe-domain phase in patterned permalloy films

{\mathrm{Mn}}_{12}

High-resolution detection of resonant frequencies of microwave resonators via magnetic measurements

. Combined with the evidence of magnetic deflagration in

Quantum tunneling of the interfaces between normal-metal and superconducting regions of a type-I Pb superconductor

{\mathrm{Mn}}_{12}

Long-range proximity effect in Nb-based heterostructures induced by a magnetically inhomogeneous permalloy layer

acetate [Y. Suzuki et al., Phys. Rev. Lett. 95, 147201 (2005)], this suggests a novel physical phenomenon: deflagration assisted by quantum tunneling.

Observation of phonon-induced magnetic deflagration in manganites

We report here on the influence of surface acoustic waves (SAWs) on the magnetization of a Mn12-acetate single crystal. The crystal was mounted on the surface of a piezoelectric LiNbO3 substrate containing an interdigital transducer for the excitation of SAWs. The magnetization of the crystal was measured using a rf superconducting quantum interference device with a time resolution of 1μs. The piezoelectric material was excited by SAW pulses of different frequencies produced by applying microwave pulses to the transducer. Our data show that molecular magnets onto the LiNbO3 surface can be used as very sensitive detectors of the SAW frequency and intensity.

Microwave absorption and magnetization tunneling in Mn 12 -acetate molecular clusters

We investigate the experimental detection of the electromagnetic radiation generated in the fast magnetization reversal in Mn12-acetate at low temperatures. In our experiments we used large single crystals and assemblies of several small single crystals of Mn12-acetate placed inside a cylindrical stainless-steel waveguide in which an InSb hot-electron device was also placed to detect the radiation. All this was set inside a SQUID magnetometer that allowed to change the magnetic field and measure the magnetic moment and the temperature of the sample as the InSb detected simultaneously the radiation emitted from the molecular magnets. Our data show a sequential process in which the fast inversion of the magnetic moment first occurs, then the radiation is detected by the InSb device, and finally the temperature of the sample increases during 15 ms to subsequently recover its original value in several hundred milliseconds.