## Zur Theorie des Ferromagnetismus (pp. 206-219) WITH Beugung von Molekularstrahlen (pp. 95-125) in Zeitschrift für Physik, Bd. 61, 1930

Berlin: Julius Springer, 1930. 1st Edition. FIRST EDITION, FULL VOLUME, OF BLOCH’S SEMINAL INTRODUCTION OF THE SPIN-WAVE (MAGNONS) THEORY OF FERROMAGNETS. Also included is an important paper by Estermann and Stern, wherein they are “the first to demonstrate wave properties of particles larger than an electron… using crystal diffraction methods utilizing beams of hydrogen and helium molecules” (History of Physics: The Wenner Collection). More information follows that on Bloch.

Bloch’s theory (also known as Bloch’s law) made it possible to both understand and explain the reduction of spontaneous magnetization in a ferromagnet. His work provided “the temperature dependence of spontaneous magnetization at low temperatures” [proving] the “decrease in spontaneous magnetization at higher temperatures is caused by the increasing excitation of spin waves” and “that the frequency of the low-energy excitations of a quantum ferromagnet scales as the square of the momentum” (Wikipedia; Fradkin, 202). Bloch’s paper introduced the idea of Magnons as the elementary excitations in ferromagnetic crystals. Bloch introduced the concept of Magnons “in order to explain the reduction of the spontaneous magnetization in a ferromagnet” (Wikipedia). “According to the laws of quantum mechanics, the reversal of a single atomic magnet is equivalent to a partial reversal of all the atomic magnets in a group. This partial reversal spreads through the solid as a wave of discrete energy transferal. This wave is called a spin wave, because the magnetism of each atom is produced by the spin of unpaired electrons in its structure. Thus, a magnon is a quantized spin wave. As the temperature of a magnetic substance is increased, its magnetic strength decreases, corresponding to the presence of a large number of magnons” (EB). Bloch’s theory introduced the concept of spin waves and “correlated the thermal excitation of magnons with the decrease of spontaneous magnetization from its saturated value at absolute zero. He set up a law that describes the temperature dependence of the decrease in magnetization, generally called the Bloch T3/2 Bloch law” (Singh, Solid State Physics, 450).

“At absolute zero temperature, a Heisenberg ferromagnet reaches the state of lowest energy, in which all of the atomic spins (and hence magnetic moments) point in the same direction. As the temperature increases, more and more spins deviate randomly from the common direction, thus increasing the internal energy and reducing the net magnetization. If one views the perfectly magnetized state at zero temperature as the vacuum state of the ferromagnet, the low-temperature state with a few spins out of alignment can be viewed as a gas of quasiparticles, in this case magnons. Each magnon reduces the total spin along the direction of magnetization by one unit of (reduced Planck's constant) and the magnetization by , where is the gyromagnetic ratio” (Wikipedia).

ALSO: Estermann and Stern “found that the intensity of the scattered beam recorded as a function of angle showed clearly discernible diffraction maxima. They also developed in great detail the theory of diffraction for beams scattering for periodic lattices, which serve as a diffraction grating for the ‘matter waves’. This work not only allowed a direct verification of the de Broglie relationship but also permitted the determination of the effective grating constant of the crystal lattice” (Zare, Otto “Stern and the Double Bank Shot”, Z. Phys. D - Atoms, Molecules and Clusters 10, 377, 1988). Item #940

CONDITION & DETAILS: Berlin: Julius Springer. Full volume. Two small stamps on the rear of the title page and very slight ghosting at the spine from the removal of a label.. Provenance: Ownership stamp on the blank flyleaf of Friedrich Hund, a German physicist known for his work on atoms and molecules. (9 x 6.5 inches). pp. 878. Black cloth boards over marbled paper; slight rubbing at the edge tips. Very solidly bound. Bright and clean inside and out. Very good +.

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Price:
$300.00
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