arXiv subjects

A. Anaya

Publications and source records attributed to A. Anaya.

5 recordsLinked to original sources

arXiv2005

Spin-Based Magnetofingerprints and Dephasing in Strongly Disordered Au-Nanobridges

We investigate quantum interference effects with magnetic field (magnetofingerprints) in strongly disordered Au-nanobridges. The magnetofingerprints are unconventional because they are caused by the Zeeman effect, not by the Aharonov-Bohm effect. These spin-based magnetofingerprints are equivalent to the Ericson's fluctuations (the fluctuations in electron transmission probability with electron energy). We present a model based on the Landauer-Buttiker formalism that describes the data. We show that the dephasing time $τ_ϕ(E,T)$ of electrons at temperature $T$ and energy $E$ above the Fermi level can be obtained from the correlation magnetic field. In samples with localization length comparable to sample size, $h/τ_ϕ(E,T) \approx E$, for $E\gg k_B T$, which shows that the Fermi liquid description of electron transport breaks down at length scale comparable to the localization length.

cond-mat.mes-hall↗

arXiv2005

Suppression of Spin-Orbit Scattering in Strong-Disordered Gold Nanojunctions

We discovered that spin-orbit scattering in strong-disordered gold nanojunctions is strongly suppressed relative to that in weak-disordered gold thin films. This property is unusual because in weak-disordered films, spin-orbit scattering increases with disorder. Granularity and freezing of spin-orbit scattering inside the grains explains the suppression of spin-orbit scattering. We propose a generalized Elliot-Yafet relation that applies to strong-disordered granular regime.

cond-mat.mes-hall↗

arXiv2004

Localization and Capacitance Fluctuations in Disordered Au Nano-junctions

Nano-junctions, containing atomic-scale gold contacts between strongly disordered leads, exhibit different transport properties at room temperature and at low temperature. At room temperature, the nano-junctions exhibit conductance quantization effects. At low temperatures, the contacts exhibit Coulomb-Blockade. We show that the differences between the room-temperature and low temperature properties arise from the localization of electronic states in the leads. The charging energy and capacitance of the nano-junctions exhibit strong fluctuations with applied magnetic field at low temperature, as predicted theoretically.

cond-mat.mes-hall↗

arXiv2002

Nanometer-Scale Metallic Grains Connected with Atomic-Scale Conductors

We describe a technique for connecting a nanometer-scale gold grain to leads by atomic-scale gold point contacts. These devices differ from previous metallic quantum dots in that the conducting channels are relatively well-transmitting. We investigate the dependence of the Coulomb blockade on contact resistance. The high-resistance devices display Coulomb blockade and the low-resistance devices display a zero-bias conductance dip, both in quantitative agreement with theory. We find that in the intermediate regime, where the sample resistance is close to $h/e^2$, the I-V curve displays a Coulomb staircase with symmetric contact capacitances.

cond-mat.mes-hall↗

arXiv2002

Electron Transport in Metallic Grains

We discuss electron transport in individual nanometer-scale metallic grains at dilution refrigerator temperatures. In the weak coupling regime, the grains exhibit Coulomb blockade and discrete energy levels. Electron-electron interactions lead to clustering and broadening of quasiparticle states. Magnetic field dependences of tunneling resonances directly reveal Kramers degeneracy and Lande g-factors. In grains of Au, which have strong spin-orbit interaction, g-factors are strongly suppressed from the free electron value. We have recently studied grains in the strong coupling regime. Coulomb blockade persists in this regime. It leads to a suppression in sample conductance at zero bias voltage at low temperatures. The conductance fluctuates with the applied magnetic field near zero bias voltage. We present evidence that the fluctuations are induced by electron spin. This paper reviews the evolving progress in interpreting these observations.

cond-mat.mes-hall↗