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We performed magneto-resistance measurements on a semi-metallic InAs–GaSb quantum well. By shining visible light on the sample, a Negative Persistent Photoconductivity effect (NPPC) was observed. Overnight illumination reduced the electron density of the sample from 9.54×1011 cm−2 to 9.04×1011 cm−2. A possible explanation for this effect is being sought in interface defect states.

We present FIR magneto-absorption experiments on InAs-GaSb heterojunctions. The results are discussed in terms of interband transitions and cyclotron resonances of a single electron (and a single hole) energy level. Fitting of the data to this model yields the position of these levels relative to the bottom of the quantum well.

The CESR linewidth of pure aluminium is shown to have a temperature dependent phonon contribution which is largely frequency independent. A second term in the linewidth is found to be temperature independent but linearly dependent upon frequency giving 0.11 mT per GHz. Finally it is shown that if partial breakdown of motional narrowing occurs it contributes a term proportional to the frequency and not, as expected, to the frequency squared.

The effect of the observational frequency upon the Conduction Electron Spin Resonance recorded from silver foils and sodium in quartz tubes is reported. For both materials an increase in frequency results in an increase in linewidth, a linear relationship being indicated for silver. We interpret some features of the results as being due to surface effects, additional evidence for the influence of the surface on CESR coming from surface treatment of copper foils.

CW saturation ESR experiments at 20.9 and 9.0 GHz have been carried out between 4.2 and 300 K on a-Si films sputtered on fused silica substrates. The ESR signal (of g = 2.0050 ± 0.0001) ascribed to dangling bonds in the a-Si network shows up to be strongly saturatable (onset of saturation at K-band microwave power PS ≲ 1μW at 4.2 K). Submitting the a-Si film subsequently to a SiO2 chemical etchant drastically decreases (PS increased by more than a factor 1500) the saturatability from where a strongly phonon-bottlenecked (PBN) spin—lattice relaxation regime is concluded to exist on the non-etched films. This PBN is ascribed to O2 contamination, enhancing the saturatability in two steps.

A reinterpretation is presented of recent results (Chizhov et al. 1982) on the conduction electron spin resonance (CESR) linewidths recorded from small lithium particles to which small levels c of sodium impurities have been added. This reanalysis demonstrates good agreement with contemporary understanding of interface spin scattering in bimetallic, layered, systems. It is shown that the sodium segregates out to the surface of the lithium particles. A maximum of three atomic layers of sodium on the surface gives rise to the observed spin-flip probability of the lithium conduction electrons at the surface, ϵ obs , being equal to ϵ Na where ϵ Na is the surface spin-flip probability for the sodium-vacuum interface. We approximate, for sufficient sodium impurities, ϵ obs = ϵ Na to σ sf , Li (Na)/ σ r , Li (Na) where σ sf , Li (Na) and σ r , Li (Na) are the spin-flip and resistivity scattering cross sections respectively for Na impurities in Li. From this relationship it is predicted that the amount of CESR linewidth broadening due to dissolved Na, is ΔB i (Na)/ c = 0.11 mT/at.%.

The exchange parameters and saturation magnetization have been measured for a large number of films of nickel-cobalt alloys. The data are obtained from standing spin wave resonance at room temperature in a conventional 9 GHz spectrometer. The distortions in the spectra are accounted for by a first order perturbation calculation. 1 The results are analysed using a model proposed by Hatherley et al . 2 Within the framework of this model values for the second moment of the exchange integral between NiNi, NiCo and CoCo pairs of atoms are derived.

Conduction-electron spin resonance in thin aluminium platelets, coated with a plastic surface layer, has been studied in a reflection spectrometer at 60 GHz. It is shown that the data on linewidth and g -factor fall in line with recent measurements at 21 GHz by the present authors and partly also with earlier measurements at 1.27 GHz 9.27 GHz, 35 GHz and 79 GHz by others.

The Tb 3+ electron paramagnetic resonances of a spherically shaped LiTbF 4 single crystal were measured with the static magnetic field along the c -axis, using an HCN laser at 890.8 and 964.3 GHz. At 4.2 K the measured spectrum consists of four hyperfine lines which have a spacing of 25.0± 0.2 mT and a width of roughly 10 mT. The g -factor is 17.75 ± 0.1 at both frequencies. In each hyperfine line of the spectrum at 4.2 K a superimposed structure is seen. This structure is explained by changes in the dispersion of the LiTbF 4 crystal.

The rise in g factor and linewidth with decreasing temperature below 30 K usually observed in CESR of aluminium samples, is almost absent in samples coated with a plastic layer. The properties of untreated samples are slowly restored after removal of the plastic layer. These observations, together with previous results on ion implanted samples, point towards interactions of the conduction electrons with a layer of localized moments on the surface.

The magnetoresistance of single crystal aluminium was measured with the magnetic field in the three main crystallographic directions [100], [110] and [111], in the temperature range 4.2–20 K and in magnetic fields up to 7 T. The exponent of a T n -law is shown to be decreasing with increasing fields.