F. Herlach

Magnetic breakdown and quantum interference in the quasi-two-dimensional superconductor in high magnetic fields

Magnetic breakdown phenomena have been investigated in the longitudinal magnetoresistance of the quasi-two-dimensional (Q2D) superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) in magnetic fields of up to 50 T, well above the characteristic breakdown field. The material is of great interest because its relatively simple Fermi surface, consisting of a closed Q2D pocket and an open Q1D band, is almost identical to the initial hypothetical breakdown network proposed by Pippard. Two frequencies are expected to dominate the magnetoresistance oscillations: the a frequency, corresponding to orbits around the closed pocket, and the beta frequency, corresponding to the simplest classical breakdown orbit. However, a beta - alpha frequency is in fact found to be the dominant high-frequency oscillation in the magnetoresistance. Numerical simulations, employing standard theories for calculating the density of states, indicate that a significant presence of the beta - alpha frequency (forbidden in the standard theories) can result simply from the frequency-mixing effects associated with the pinning of the chemical potential in a quasi-two-dimensional system. While this effect is able to account for the previous experimental observation of beta - alpha frequency oscillations of small amplitude in the magnetization, it cannot explain why such a frequency dominates the high-field magnetotransport spectrum. Instead we have extended the numerical simulations to include a quantum interference model adapted for longitudinal magnetoresistance in a quasi-two-dimensional conductor. The modified simulations are then able to account for most of the features of the experimental magnetoresistance data.

Deformation analysis of pulsed magnets with internal and external reinforcement

Stresses and strains in the mid-plane of a pulsed magnet are analytically calculated by solving the system of equations describing the displacement in each layer of the coil. Nonlinear stress-strain characteristics and the propagation of plastic deformation are taken into account by sub-dividing each layer of the coil in the radial direction and changing the elastic-plastic matrix at each transition point. The effects of pre-stressing during winding and thermal stresses are calculated and discussed. Two coils that have been tested up to 60-70 T fields are described as examples. It is shown that, under some conditions, elastic-plastic cycling leads to a stable state, whereas in others this results in runaway deformation that leads to coil destruction after a few cycles.

Efficient Design of Advanced Pulsed Magnets

The algorithms and basic equations used in the ldquoPMDSrdquo code for efficient coil design are described. The code calculates stresses and heating in the mid-plane only; there they are highest. The pulse shape is calculated for a capacitor discharge and for a voltage waveform derived from a generator. As examples, the optimization of a monolithic coil and a dual magnet are discussed, the latter based on the European ldquoARMSrdquo magnet. The influence of materials data on magnet performance is discussed.

Magnetotransport in a pseudomorphic gaas/ga0.8in0.2as/ga0.75al0.25as heterostructure with a si delta-doping layer

Magnetotransport properties of a pseudomorphic GaAs/

The Pulsed High Magnetic Field Facility at HUST, Wuhan, China and Associated Magnets

{\mathrm{Ga}}_{0.8}

A probe for magnetization measurements of thin superconducting films in pulsed high magnetic fields

{\mathrm{In}}_{0.2}

Magnet laboratory facilities worldwide—An update

As/

Pulsed magnet design software

{\mathrm{Ga}}_{0.75}