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Papers by Javier Gomez
Chemical Physics Letters, 2010
We discuss in detail spin-polarized electronic structure calculations for the 1 Â 1 YBa 2 Cu 3 O ... more We discuss in detail spin-polarized electronic structure calculations for the 1 Â 1 YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattice. Our results are based on the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The on-site Coulomb interaction affecting the correlated Cu 3d and Pr 4f electrons is taken into consideration. At first glance the YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 interface appears to be inert, i.e., the electronic states do not show a clear sign of interaction between the two component materials. Nonetheless, a total energy analysis points to a significant modification of the magnetic coupling in the vicinity of the interface due to the relaxation of the electronic structure.
physica status solidi (b), 2009
We calculate current, spin current and tunnel magnetoresistance (TMR) for a quantum dot coupled t... more We calculate current, spin current and tunnel magnetoresistance (TMR) for a quantum dot coupled to ferromagnetic leads in the presence of a square wave of bias voltage. Our results are obtained via time-dependent nonequilibrium Green function. Both parallel and antiparallel lead magnetization alignments are considered. The main findings include a wave of spin accumulation and spin current that can change sign as the time evolves, spikes in the TMR signal and a TMR sign change due to an ultrafast switch from forward to reverse current in the emitter lead.
We observe for the first time a structural phase transition in the oxyborate Fe 3 O 2 BO 3 which ... more We observe for the first time a structural phase transition in the oxyborate Fe 3 O 2 BO 3 which occurs along three leg ladders present in this material. X-ray diffraction shows that this transition at 283 K is associated with a new phase where atomic displacements occur in alternate directions perpendicular to the axis and within the plane of the ladders. Magnetic data show that these displacements lead to the formation of singlet pairs which dissociate close to the structural transition. Anomalies in the transport properties also occur close to 283 K showing that the structural transition is related to a charge ordering phenomenon in a low dimensional structure.
Chemical Physics Letters, 2010
We discuss in detail spin-polarized electronic structure calculations for the 1 Â 1 YBa 2 Cu 3 O ... more We discuss in detail spin-polarized electronic structure calculations for the 1 Â 1 YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 superlattice. Our results are based on the full-potential linear augmented plane wave method and the generalized gradient approximation for the exchange-correlation functional. The on-site Coulomb interaction affecting the correlated Cu 3d and Pr 4f electrons is taken into consideration. At first glance the YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 interface appears to be inert, i.e., the electronic states do not show a clear sign of interaction between the two component materials. Nonetheless, a total energy analysis points to a significant modification of the magnetic coupling in the vicinity of the interface due to the relaxation of the electronic structure.
physica status solidi (b), 2009
We calculate current, spin current and tunnel magnetoresistance (TMR) for a quantum dot coupled t... more We calculate current, spin current and tunnel magnetoresistance (TMR) for a quantum dot coupled to ferromagnetic leads in the presence of a square wave of bias voltage. Our results are obtained via time-dependent nonequilibrium Green function. Both parallel and antiparallel lead magnetization alignments are considered. The main findings include a wave of spin accumulation and spin current that can change sign as the time evolves, spikes in the TMR signal and a TMR sign change due to an ultrafast switch from forward to reverse current in the emitter lead.
We observe for the first time a structural phase transition in the oxyborate Fe 3 O 2 BO 3 which ... more We observe for the first time a structural phase transition in the oxyborate Fe 3 O 2 BO 3 which occurs along three leg ladders present in this material. X-ray diffraction shows that this transition at 283 K is associated with a new phase where atomic displacements occur in alternate directions perpendicular to the axis and within the plane of the ladders. Magnetic data show that these displacements lead to the formation of singlet pairs which dissociate close to the structural transition. Anomalies in the transport properties also occur close to 283 K showing that the structural transition is related to a charge ordering phenomenon in a low dimensional structure.