Observation of Magnetic Ripple and Nanowidth Domains in a Layered Ferromagnet

Abstract

We investigated ferromagnetic domain structures on nanometer to micrometer scale for single crystals of a layered ferromagnet, La(2-2x)Sr(1+2x)Mn2O7 (0.32 < or = x < or = 0.40), as functions of x and temperature by means of Lorentz electron microscopy. We have succeeded in observing the evolution of magnetic ripple structure, dynamically, related to a spin reorientation transition where the magnetization direction switches between parallel and perpendicular to the layers. Our high-resolution magnetic domain imaging revealed that the ripple state is characterized by the evolution of magnetic nanowidth domains.

Observation of magnetic domain structures in La1-xSrxMnO3

“…In fact, recently, the characteristic magnetic domains which are related to the crystal structure have been observed in a layered manganite, using Lorentz transmission electron microscopy (LTEM) [2]. La 1Àx Sr x MnO 3 is a typical CMR manganite with a ferromagnetic metallic state [2]. This system exhibits the structural phase transitions with changes of the chemical composition, i.e.…”

“…A magnetic domain structure in the manganites is expected to have a wide variety, because the state is very sensitive to a change in the crystal structure, as well as in the electronic structure [1]. In fact, recently, the characteristic magnetic domains which are related to the crystal structure have been observed in a layered manganite, using Lorentz transmission electron microscopy (LTEM) [2]. La 1Àx Sr x MnO 3 is a typical CMR manganite with a ferromagnetic metallic state [2].…”

Search for heavy neutrinos in π → μν decay

“…In general, the mass scale of heavy neutrinos is unknown opening up many possibilities and potential observables in particle physics, astrophysics and cosmology. In the Neutrino Minimal Stan-dard Model (νMSM) three sterile neutrinos are introduced which include a stable dark matter candidate [8]. MeV neutrinos could be accommodated in the νMSM to explain the 7 Li abundance [9] or, with the addition of a MeV scalar, obtain consistent results for anomalies in neutrino experiments [10].…”

Ferromagnetic domain structures and spin configurations measured in doped manganite

“…[2][3][4][5] Accordingly, magnetic domains and domain walls in the FM phase of these oxides may strongly affect not only their magnetic properties but also their electron-transport properties. [6][7][8][9] However, the electrical resistance of the magnetic domain walls critically rests upon the domain's configuration [10][11][12] because the reversal of magnetization at a domain wall in the interrupted perovskite crystal significantly scatters the charge carriers. A precise analysis and understanding of the magnetic microstructure is then vitally important for the fundamental understanding of advanced functional magnetic materials.…”