Wikinventia — Atlas of discoveries and inventions · Global Age

Quantum motive force of the Berry phase — Ady Stern

1992 AD · Transmission: Global
PhysicsTheoryHebrew

Ady Stern, then a doctoral student at the Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel Aviv University (with a stay at the Institute for Theoretical Physics, UC Santa Barbara), publishes in 1992 "Berry's Phase, Motive Forces, and Mesoscopic Conductivity". The paper takes up the framework Loss, Goldbart, and Balatsky had established in 1990 for the static case — a mesoscopic ring in a spatially fixed, non-uniform magnetic field — and extends it to the dynamic case: what happens if that magnetic texture, and therefore the accumulated Berry phase, also varies in time? Stern shows that a time-dependent Berry phase induces a real motive force in the ring, in strict analogy with Faraday's law: just as a varying magnetic flux induces an electromotive force coupled to electric charge, a varying Berry phase induces a motive force coupling directly to the electron's spin. Stern also formalizes, for the static case, the exact equivalence between the Berry phase accumulated by the spin and the conventional Aharonov-Bohm effect on the ring's conductance. The work shows that the Berry phase has dynamic, measurable consequences for electronic transport in mesoscopic systems, beyond its earlier interpretation as a geometric property of static energy levels, and anticipates the field of spin motive forces within spintronics.

InstitutionRaymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel Aviv University; Institute for Theoretical Physics, University of California, Santa Barbara
Historical regionIsrael (Tel Aviv) — with a stay in the United States (Santa Barbara, California)
Primary sourceStern, A. — "Berry's Phase, Motive Forces, and Mesoscopic Conductivity" (Physical Review Letters, 68(7), 1022-1025, 1992). DOI: 10.1103/PhysRevLett.68.1022
Secondary sourceLoss, D., Goldbart, P. & Balatsky, A.V. — "Berry's Phase and Persistent Charge and Spin Currents in Textured Mesoscopic Rings" (Physical Review Letters, 65, 1655, 1990) — the static framework Stern extends to the dynamic case
Original languageEnglish
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