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Spin waves in itinerant ferromagnets with Hund's coupling
Vol. 15, No. 1 .
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
MAGNETISM IN G O L D - I R O N ALLOYS BELOW 14 at.% Fe B. de Mayo, Metallurgy Department and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, U.S.A.
The dependence of the magnetization on temperature and on magnetic field for Au alloys with 5, 10 and 13.8 at.% Fe has been measured. The gradual freezing of the spin orientations on cooling, time dependence, and thermomagnetic history effects characteristic of mictomagnetism are found. This magnetic behavior, occurring in disordered alloys, can be described in terms of a 'spin glass' matrix with magnetic clusters. Metallurgical treatment strongly affects the cluster sizes and concentrations and the magnetization. The 'Curie temperatures' observed by earlier Mossbauer measurements apparently correspond to the freezing of the 'spin glass' matrix.
Received 22 May 1972 Revised 12 April 1973 10.
Received 15 October 1973
11. CURRENT SATURATION IN CdS P.K. Lai, P.O. Massicot and S.J° Nettel, Department of Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12181, U.S.A.
An iteration procedure for calculating the high electric fields found in piezoelectric semi-conductors beyond the onset of current saturation is described. The procedure uses a wave equation derived from the well known formula for electron mobility of Feynman, Hellwarth, Iddings and Platzman in which the lattice coordinates have been removed. The zero order state in the procedure is that of electrons pursuing a constant velocity path, (infinite effective mass approximation), the velocity being taken at a phase velocity of acoustic shear modes..To next order electrons are bound by and oscillate in a quasi-potential, which itself travels at the shear wave velocity. Electrons in a single well act coherently in producing a potential strong enough to bind them despite their Coulomb repulsion. We estimate the number of electrons bunched into a single droplet, as well as the electric field to sustain this motion, i.e. the field in the high field domain.
THERMAL EXPANSION AND MODE GRONEISEN PARAMETERS OF LiH AND LiD H. Jex, Institut Max von Laue, Paul Langevin, BP 156 Centre de tri, 38 042 Grenoble Cedex, France.
The third order contribution of the shell-shell interaction between next nearest neighbours has been determined from a calculation of the coefficient of linear thermal expansion of LiH and 7 LiD. The Coulomb anharmonicity is included. A shell model fitted to phonon energies from inelastic neutron scattering in 7 LiD was used. From this model then averaged Griineisen constants and individual mode Griineisen parameters have been deduced.
Received I0 September 1971 Revised 18 January 1974
9.
vii
SPIN WAVES IN ITINERANT FERROMAGNETS WITH HUND'S COUPLING A. Sukiennicki and A. Zag6rski, Institute of Physics, Technical University, Warsaw, Poland.
Spin waves in Zener-like model of ferromagnetism with the intra-atomic Hund's coupling are considered. Dispersion relations for both acoustical and optical branches are calculated. The spin-wave effective mass for the acoustical branch in the case of Ni and Fe is discussed and a qualitatively agreement with experimental data is found.
Received 2 January 1973
12.
HIGH-PRESSURE SYNTHESIS OF/3-WTYPE Nb3 Te John F. Cannon, Donald L. Robertson and H. Tracy Hall, Department of Chemistry, Brigham Young University, Provo, Utah 84602, U.S.A.A.C. Lawson, Institute for Pure and Applied Physical Sciences, University of California, San Diego, La JoUa, California 92037, U.S.A.
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
MAGNETISM IN G O L D - I R O N ALLOYS BELOW 14 at.% Fe B. de Mayo, Metallurgy Department and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, U.S.A.
The dependence of the magnetization on temperature and on magnetic field for Au alloys with 5, 10 and 13.8 at.% Fe has been measured. The gradual freezing of the spin orientations on cooling, time dependence, and thermomagnetic history effects characteristic of mictomagnetism are found. This magnetic behavior, occurring in disordered alloys, can be described in terms of a 'spin glass' matrix with magnetic clusters. Metallurgical treatment strongly affects the cluster sizes and concentrations and the magnetization. The 'Curie temperatures' observed by earlier Mossbauer measurements apparently correspond to the freezing of the 'spin glass' matrix.
Received 22 May 1972 Revised 12 April 1973 10.
Received 15 October 1973
11. CURRENT SATURATION IN CdS P.K. Lai, P.O. Massicot and S.J° Nettel, Department of Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12181, U.S.A.
An iteration procedure for calculating the high electric fields found in piezoelectric semi-conductors beyond the onset of current saturation is described. The procedure uses a wave equation derived from the well known formula for electron mobility of Feynman, Hellwarth, Iddings and Platzman in which the lattice coordinates have been removed. The zero order state in the procedure is that of electrons pursuing a constant velocity path, (infinite effective mass approximation), the velocity being taken at a phase velocity of acoustic shear modes..To next order electrons are bound by and oscillate in a quasi-potential, which itself travels at the shear wave velocity. Electrons in a single well act coherently in producing a potential strong enough to bind them despite their Coulomb repulsion. We estimate the number of electrons bunched into a single droplet, as well as the electric field to sustain this motion, i.e. the field in the high field domain.
THERMAL EXPANSION AND MODE GRONEISEN PARAMETERS OF LiH AND LiD H. Jex, Institut Max von Laue, Paul Langevin, BP 156 Centre de tri, 38 042 Grenoble Cedex, France.
The third order contribution of the shell-shell interaction between next nearest neighbours has been determined from a calculation of the coefficient of linear thermal expansion of LiH and 7 LiD. The Coulomb anharmonicity is included. A shell model fitted to phonon energies from inelastic neutron scattering in 7 LiD was used. From this model then averaged Griineisen constants and individual mode Griineisen parameters have been deduced.
Received I0 September 1971 Revised 18 January 1974
9.
vii
SPIN WAVES IN ITINERANT FERROMAGNETS WITH HUND'S COUPLING A. Sukiennicki and A. Zag6rski, Institute of Physics, Technical University, Warsaw, Poland.
Spin waves in Zener-like model of ferromagnetism with the intra-atomic Hund's coupling are considered. Dispersion relations for both acoustical and optical branches are calculated. The spin-wave effective mass for the acoustical branch in the case of Ni and Fe is discussed and a qualitatively agreement with experimental data is found.
Received 2 January 1973
12.
HIGH-PRESSURE SYNTHESIS OF/3-WTYPE Nb3 Te John F. Cannon, Donald L. Robertson and H. Tracy Hall, Department of Chemistry, Brigham Young University, Provo, Utah 84602, U.S.A.A.C. Lawson, Institute for Pure and Applied Physical Sciences, University of California, San Diego, La JoUa, California 92037, U.S.A.