Uber die Spektra von Atomsystemen mit zwei Elektronen (Heisenberg) in Zeitschrift für Physik, Vol. 39, 1926, pp. 499-518 WITH Zur theorie des ferromagnetismus (Heisenberg, pp. 619-636) WITH Elementare Theorie magnetischer und elektrischer Eigenschaften der Metalle beim absoluten Nullpunkt der Temperatur (Fenkel, pp. 31-45) in Zeitschrift für Physik Vol. 49, 1928

Berlin: Julius Springer. 1st Edition. FIRST EDITION, FIRST ISSUE OF TWO SEMINAL PAPERS: Heisenberg's groundbreaking contribution to magnetism and to the identification of the quantum mechanical exchange energy. A third paper of import appears in the 1928 volume, Jacov Frankel's collectivized model of the quantum theory of ferromagnetism. Heisenberg's model appears in the same volume, was submitted after Frenkel's, and presents the model of localized spins.

"Heisenberg's masterly contribution in magnetism lies in identifying the quantum mechanical exchange energy, first appearing in the context of chemical bonding and spectroscopy, to be of central importance in explaining ferromagnetism... The question was this: If every atom has an outer cloud of electrons, then how do atoms approach each other to form a chemical bond? It was Heisenberg who showed that the interaction between electrons, called the exchange energy," was the key (ibid., 60). His "exchange interaction" is a force generated solely by the exchange of positions of two totally indistinguishable quantum particles - "a quantum mechanical effect which increases or decreases the expectation value of the energy or distance between two or more identical particles when their wave functions overlap" (Wikipedia).

In the early 20th century physicists did not understand ferromagnetism on an atomic basis. "It was Heisenberg's work in the late 1920's that filled this void. To accomplish this, quantum mechanics had to be discovered first... It was indeed in the fitness of things that the quantum dynamics of the electron left an imprint on another area, namely magnetism, which too had to do with the magnetic effects of electron dynamics" (ibid., 58). What Heisenberg began to understand was the connection between ferromagnetism and electron bonding, two areas that most physicists believed were wholly unconnected phenomena. "It was Heisenberg, who saw the connection and established it in two seminal papers, written in 1926 and 1928 [the two papers offered here]" (Chatterjee, "Heisenberg and Ferromagnetism," Resonance, 2004, 63-64).

WITH BOUND, FRENKEL'S " Elementare Theorie magnetischer und elektrischer Eigenschaften der Metalle beim absoluten Nullpunkt der Temperatur"(Fenkel, pp. 31-45) in Zeitschrift für Physik Vol. 49, 1928, pp. 31-45. Frankel's paper, ‘On the Magnetic and Electrical Properties of Metals at Absolute Zero' speculates "that a spontaneous magnetic moment can appear as a consequence of a coupling arising from Heisenberg's resonance phenomenon between the individual spin moments of the free electrons, and between the spin vectors of the free and bound electrons, ‘yielding, in certain circumstances, an unusually large negative value for the ‘magnetic' energy. However, unlike Heisenberg, Frenkel did not develop this suggestion into a quantitative theory. No mention of Frankel's paper appears either in Heisenberg's publications or in his letters to Pauli" (Hoddeson, Out of the Crystal Maze, 132). CONDITION & DETAILS: Berlin: Julius Springer. 4to. (9 x 6.5 inches; 225 x 163mm). Two full volumes. Zeitschrift für Physik Volumes 39 and 49. Handsomely bound in black cloth over marbled paper boards; library labels removed with slight ghosting visible. Very minor rubbing at the edges on Volume 39. Both tightly and solidly bound. Near pristine throughout the interior.