Vol. 19, No. 1 (1963)
1963-01-05
CONTENT
1963, 19 (1): 1-10.
doi: 10.7498/aps.19.1
Abstract +
The magnetic properties and Ferromagnetic resonance of the yttrium-lanthanum iron garnet system Y3(1-x)La3xFe5O12 were investigated at the compositions corresponding to x=0, 0.05, 0.10, 0.20, 0.30, 0.50, 0.75 and 1.00. The single-phase region with garnet structure determined by the X-ray powder pattern analysis and metallographic observations extends to about 0.10s, initial permeability μ0, coercive force Hc, effective g-factors geff and resonance line-width △H (at 3970 and 9160 Mc) were measured as a function of composition. The variation of σs with composition and the magnitude of μ0 as viewed from various magnetization mechanisms were discussed. From the frequency dependence of geff, the intrinsic g-factors and internal fields Hi of the materials were calculated. Exponential dependence of △H, Hi and Hc on x in certain composition region was observed experimentally and interpreted from the point of view of magnetic inhomogene-ities.
1963, 19 (1): 11-24.
doi: 10.7498/aps.19.11
Abstract +
A two-meter normal incidence vacuum ultra-violet spectrograph has been built and in operation for some time. The spectrograph has an angle of incidence 7.5° and covers the spectral range 2100?-200?, with an average dispersion 8.7?/mm. A low pressure condensed spark discharge tube is used as the source, giving intense sharp spectral lines of various degree of ionization. Majority (554 in number) of the emission lines has been identified.
1963, 19 (1): 25-48.
doi: 10.7498/aps.19.25
Abstract +
A theory is proposed for the impurity-induced tunnelling current which apparently constitutes the major part of the current observed in As and P doped germanium tunnel diodes. The experimental valley-orbit splittings of various donors in. germanium show-that the short range atomic fields of As and P are many times stronger than that of Sb and, for doping levels above 1019/cm3, can be equally or more effective in scattering than phonons. The possible mechanisms for tunnelling caused by impurity scattering are examined; it is found that owing to a special feature of the germanium band structure, namely, (0, 0, 0) conduction band minimum not too high and associated with a particularly small effective mass, a second order process via the (0, 0, 0) minimum should be the dominant process. A method for treating such a second order process is developed, which gives a clear quasi-classical picture of the tunnelling process: an electron tunnelling from a conduction band minimum, when reaching an optimum depth, is scattered inta (0, 0, 0) states and proceeds thereon to the valence band maximum much as in direct tunnelling. An explicit expression for the current is obtained; the magnitude of the current is estimated and a comparison with a similar phonon-assisted current (see accompanying paper II) is made. It is also shown that despite the anisotropic nature of the conduction band minima, the second order current should be nearly direction-independent.
1963, 19 (1): 49-59.
doi: 10.7498/aps.19.49
Abstract +
The present paper is a sequel to the accompanying paper I, where a theory is given for the impurity-induced current in germanium tunnel diodes. It is pointed out that for reasons similar to those given in connexion with the impurity-induced current, the phonon-assisted current in germanium diodes should be attributed to a second order process via (0, 0, 0) conduction band minimum rather than the first order process hitherto assumed. By methods similar to those developed in I, the second order current expression is deduced and discussed; in particular, symmetry arguments indicate that for the second order process in germanium diodes, the longitudinal acoustic phonons should be by far the most effective, in agreement with existing experimental evidences.
1963, 19 (1): 60-69.
doi: 10.7498/aps.19.60
Abstract +
A proton electrostatic accelerator of the high pressure type is described. The protons accelerated by this accelerator have a maximum energy of 2.3 Mev, while 2.5 Mev momentary. It has been in operation for more than four years.
