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- Title
Accessing the fundamentals of magnetotransport in metals with terahertz probes.
- Authors
Jin, Zuanming; Tkach, Alexander; Casper, Frederick; Spetter, Victor; Grimm, Hubert; Thomas, Andy; Kampfrath, Tobias; Bonn, Mischa; Kläui, Mathias; Turchinovich, Dmitry
- Abstract
Spin-dependent conduction in metals underlies all modern magnetic memory technologies, such as giant magnetoresistance (GMR). The charge current in ferromagnetic transition metals is carried by two non-mixing populations of sp-band Fermi-level electrons: one of majority-spin and one of minority-spin. These electrons experience spin-dependent momentum scattering with localized electrons, which originate from the spin-split d-band. The direct observation of magnetotransport under such fundamental conditions, however, requires magnetotransport measurements on the same timescale as the electron momentum scattering, which takes place in the sub-100 fs regime. Using terahertz electromagnetic probes, we directly observe the magnetotransport in a metallic system under the fundamental conditions, and determine the spin-dependent densities and momentum scattering times of conduction electrons. We show that traditional measurements significantly underestimate the spin asymmetry in electron scattering, a key parameter responsible for effects such as GMR. Furthermore, we demonstrate the possibility of magnetic modulation of terahertz waves, along with heat- and contact-free GMR readout using ultrafast terahertz signals.
- Subjects
MAGNETORESISTANCE; NUCLEAR spin; TERAHERTZ technology; MAGNETIC memory (Computers); FERROMAGNETIC materials; FERMI level
- Publication
Nature Physics, 2015, Vol 11, Issue 9, p761
- ISSN
1745-2473
- Publication type
Article
- DOI
10.1038/nphys3384