title: The anomalous Hall effect and magnetic monopoles in momentum space.
abstract: 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, approximately 10(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 (approximately 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 SrRuO3 that provide evidence for the magnetic monopole in the crystal momentum space.
authors.affiliation: Spin Superstructure Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Corporation, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 4, Tsukuba 305-8562, Japan. z.fang@aist.go.jp
authors.forename: Zhong
authors.initials: Z
authors.lastname: Fang
authors.forename: Naoto
authors.initials: N
authors.lastname: Nagaosa
authors.forename: Kei S
authors.initials: KS
authors.lastname: Takahashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Asamitsu
authors.forename: Roland
authors.initials: R
authors.lastname: Mathieu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ogasawara
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamada
authors.forename: Masashi
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Tokura
authors.forename: Kiyoyuki
authors.initials: K
authors.lastname: Terakura