Biomedical subjects

T Guidi

Publications and source records attributed to T Guidi.

3 recordsLinked to original sources

PubMed2003

Elementary excitations in the cyclic molecular nanomagnet Cr8.

Combining recent and new inelastic neutron scattering data for the molecular cyclic cluster Cr8 produces a deep understanding of the low lying excitations in bipartite antiferromagnetic Heisenberg rings. The existence of the L band, the lowest rotational band, and the E band, essentially spin wave excitations, is confirmed spectroscopically. The different significance of these excitations and their physical nature is clearly established by high-energy and Q-dependence data.

Journal Article↗

PubMed2003

Structural transformation induced by magnetic field and "colossal-like" magnetoresistance response above 313 K in MnAs.

MnAs exhibits a first-order phase transition from a ferromagnetic, high-spin metal hexagonal phase to a paramagnetic, lower-spin insulator orthorhombic phase at T(C)=313 K. Here, we report the results of neutron diffraction experiments showing that an external magnetic field, B, stabilizes the hexagonal phase above T(C). The phase transformation is reversible and constitutes the first demonstration of a bond-breaking transition induced by a magnetic field. The field-induced phase transition is accompanied by an enhanced magnetoresistance of about 17% at 310 K. The phenomenon appears to be similar to that of the colossal magnetoresistance response observed in the Mn [corrected] perovskite family.

Journal Article↗

PubMed2001

Driven kinks in discrete chains: phonon damping.

Phonon radiation is shown numerically to damp the motion of a relativistically driven straight phi(4) soliton, even in the extremely weak discreteness limit. At higher discreteness, the soliton mobility is characterized by a discontinuous dependence on the driving force; jumps are related to phonon and breather-radiation thresholds. Moreover, the speed of a frictionless soliton cannot be lowered below a certain threshold value, or else it might get trapped between two adjacent chain sites.

Journal Article↗