The Anomalous Hall Effect and Magnetic Monopoles in Momentum Space

• Published in: Science (American Association for the Advancement of Science) Vol. 302; no. 5642; pp. 92 - 95
• Main Authors: Fang, Zhong, Nagaosa, Naoto, Takahashi, Kei S., Asamitsu, Atsushi, Mathieu, Roland, Ogasawara, Takeshi, Yamada, Hiroyuki, Kawasaki, Masashi, Tokura, Yoshinori, Terakura, Kiyoyuki
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 03.10.2003; The American Association for the Advancement of Science
• Subjects: Abstract spaces; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Crystals; Electromagnetism; Electron density of states and band structure of crystalline solids; Electron states; Electronic transport in condensed matter; Exact sciences and technology; Ferromagnetism; Galvanomagnetic and other magnetotransport effects; Hall effect; Magnetic fields; Magnetic monopoles; Magnetization; Mathematical vectors; Other inorganic compounds; Physics; Single crystals; Superconductivity; Temperature dependence; Wave functions; Japan; Electrical conductivity; Magnetization; Ternary compounds; Berry phase; Calcium compounds; Hall effect; Electronic density of states; Experimental study; Magnetic monopoles; Ruthenates; Momentum space; Strontium compounds; Density functional method; Anomaly; Quaternary compounds
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1089408

Efforts to find the magnetic monopole in real space have been made in cosmic rays and in particle accelerators, but there has not yet been any firm evidence for its existence because of its very heavy mass,$\sim10^{16}$giga-electron volts. We show that the magnetic monopole can appear in the crystal momentum space of solids in the accessible low-energy region (~0.1 to 1 electron volts) in the context of the anomalous Hall effect. We report experimental results together with first-principles calculations on the ferromagnetic crystal SrRuO3that provide evidence for the magnetic monopole in the crystal momentum space.