Emergence of bound states in ballistic magnetotransport of graphene antidots

An experimental method for detection of bound states around an antidot formed from a hole in a graphene sheet is proposed by measuring the ballistic two terminal conductances. In particularly, we consider the effect of bound states formed by magnetic field on the two terminal conductance and show that one can observe Breit-Wigner like resonances in the conductance as a function of the Fermi level close to the energies of the bound states. In addition, we develop a new numerical method in which the computational effort is proportional to the linear dimensions, instead of the area of the scattering region beeing typical for the existing numerical recursive Green's function method.Comment: 7 pages, 6 figure

Anomalous Hall effect in (In,Mn)Sb dilute magnetic semiconductor

High magnetic field study of Hall resistivity in the ferromagnetic phase of (In,Mn)Sb allows one to separate its normal and anomalous components. We show that the anomalous Hall term is not proportional to the magnetization, and that it even changes sign as a function of magnetic field. We also show that the application of pressure modifies the scattering process, but does not influence the Hall effect. These observations suggest that the anomalous Hall effect in (In,Mn)Sb is an intrinsic property and support the application of the Berry phase theory for (III,Mn)V semiconductors. We propose a phenomenological description of the anomalous Hall conductivity, based on a field-dependent relative shift of the heavy- and light-hole valence bands and the split-off band

A Comparison Of Hip And Knee Joint Kinematics Between Two Alpine Ski Ergometers

This study was conducted to determine if hip and knee joint kinematics differed between conditions as subjects "skied" on two alpine ski ergometers. Eleven male recreational skiers, ages 18-23, participated in the study. During the random test, sagittal plane motions of the hip and knee joints were videotaped as subjects skied on each ski ergometer at a slow speed (92 turns/minute) and a fast speed (102 turns/minute). Each subject was vid.eotaped at 30 frames per second during the last thirty seconds of a two minute exercise bout. Three turns were randomly selected and digitized on the Ariel Performance Analysis System (APAS). Relative angular displacements of the left hip and knee were measured and compared. Hip and knee flexion were significantly different between the two ergometers at the fast speed. A comparison of the fast and slow trials revealed that subjects were able to achieve more knee flexion at the fast speed on one ergometer. However, on the other ergometer, the degree of knee flexion was greater at the slow speed. How closely the two ski ergometers simulate actual downhill skiing is unknown and warrants further investigation

Nanoscale spin-polarization in dilute magnetic semiconductor (In,Mn)Sb

Results of point contact Andreev reflection (PCAR) experiments on (In,Mn)Sb are presented and analyzed in terms of current models of charge conversion at a superconductor-ferromagnet interface. We investigate the influence of surface transparency, and study the crossover from ballistic to diffusive transport regime as contact size is varied. Application of a Nb tip to a (In,Mn)Sb sample with Curie temperature Tc of 5.4 K allowed the determination of spin-polarization when the ferromagnetic phase transition temperature is crossed. We find a striking difference between the temperature dependence of the local spin polarization and of the macroscopic magnetization, and demonstrate that nanoscale clusters with magnetization close to the saturated value are present even well above the magnetic phase transition temperature.Comment: 4 page

Evidence for localization and 0.7 anomaly in hole quantum point contacts

Quantum point contacts implemented in p-type GaAs/AlGaAs heterostructures are investigated by low-temperature electrical conductance spectroscopy measurements. Besides one-dimensional conductance quantization in units of $2e^{2}/h$ a pronounced extra plateau is found at about $0.7(2e^{2}/h)$ which possesses the characteristic properties of the so-called "0.7 anomaly" known from experiments with n-type samples. The evolution of the 0.7 plateau in high perpendicular magnetic field reveals the existence of a quasi-localized state and supports the explanation of the 0.7 anomaly based on self-consistent charge localization. These observations are robust when lateral electrical fields are applied which shift the relative position of the electron wavefunction in the quantum point contact, testifying to the intrinsic nature of the underlying physics.Comment: 4.2 pages, 3 figure