"Magnetic and transport properties of MnSi thin films"
Ms. Josefin Engelke

Sep 19, 2013

トポロジー理工学教育研究センター第192回エンレイソウの会 ・ 物理学会北海道支部講演共催
講演題目: Magnetic and transport properties of MnSi thin films
講 師 : Ms. Josefin Engelke
     Technische Universitat Braunschweig, Institute for Condensed Matter Physics, 38106 Braunschweig, Germany
日 時 : 平成25年9月19日 (木) 15:00-16:00
場 所 : 北海道大学理学部2号館211室(2-2-11)

要 旨 :
MnSi offers a variety of different magnetic phases. The competition of ferromagnetic exchange with the Dzyaloshinskii-Moriya interaction causes a helical spin structure as the ground state of the system. In applied magnetic fields a conical structure and ferromagnetic spin alignment can be observed. In addition, a skyrmion lattice phase occurs in a small field and temperature region close to the ordering temperature, which is known as the A-phase. In thin films a larger skyrmionic phase is expected in the magnetic phase diagram due to surface effects and strain. Using molecular beam epitaxy MnSi thin films have been grown on Si(111) substrates. Magnetization and magnetoresistivity measurements have been carried out and related to the magnetic phase diagram. The magnetic ordering temperature T_ord is enhanced and shows a thickness dependence. In comparison to bulk MnSi also the critical magnetic fields of the thin films are enhanced. Furthermore several features can be identified occuring in the magnetization as well as in the magnetoresistivity measurements, which are not present in bulk material. Potentially these are indications of an enlarged skyrmionic phase.
Reference: "Spin-spin correlation length in MnSi thin film", J. Engelke, T. Reimann, L. Hoffmann, S. Gas, S. Sullow, D. Menzel, J. Phys. Soc. Jpn. 81 (2012) 124709.

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